(Note that in this context 1 turn KO refers to waiting until you have no cards left in your deck and dropping your opponent from full HP with brawl, or a combination of brawl + normal attack. Former gets you mid-turn bonus.)
Akan: Unless he gets really early unstable gases/fire storms and ends up blowing your SoFos not a whole lot he can do. Easy (to 1 turn KO).
Antiaverage: While he probably won't kill you a combination of pandemonium + butterfly effect can delay you long enough you'll end up decking out. IMPORTANT: Don't nuke your SoPa until you can kill him on your current turn - that way you should avoid his antimatters. Brawl halves the required damage assuming no creatures are blocking you. Unpredictable. Either you 1 turn KO him or you lose.
Anubis: Bloodsuckers really like infecting your GP'd SoFo for some reason. Rest depends pretty much on how badly your otys get infected, cloak and steal are annoying but shouldn't be gamechanging. Try to save at least one purify for otys so they can eat more bloodsuckers. You might want to keep a skeleton or two alive so your GP'd SoFo can keep nuking his boneyards, cloaks, bone walls or whatever. Medium, bone wall is a PITA so odds are you can't 1 turn KO.
Atomsk: Barring crappy draws (including all your inertias getting stolen...) fairly straightforward. Has some burst potential so keep that GP'd SoFo topped up. And eat the damn towers or he'll steal everything. Easy (to 1 turn KO).
Bernoulli: Conveniently lowers everything to 1hp so you don't even need SoPa to eat things with your otys. Might just utterly obliterate you on the first turn or two. Easy (to 1 turn KO).
Cardinal: Fractal might turn the game around. Make sure you have a SoFo capable of eating hourglasses available all the time. Eat some of the towers so you can quanta lock him. Easy, time barrier makes 1 turn KO somewhat difficult though.
Gobannus: As usual, either he burns all your cards on turn 1 or loses. Easy (to 1 turn KO).
Halwn: Plagues (+ epidemic) might end up killing you. Medium-hard, don't attempt a 1 turn KO, just get him down asap.
Higgs: Can throw crazy mad amounts of damage out early and prevent you from playing your SoFo by having an unstable gas up. Magma makes your otys sad. Easy-Medium, if you attempt to 1 turn KO him keep in mind he might draw a SoBra and deck you out.
Hydrax: Lots of damage and ricochet freeze is nasty, it can turn a "won" game around at the last second. It helps to keep in mind brawl works through freeze so you can use it to kill his crusaders if SoPa has buffed your creatures enough.
Janus: Short of fractal has no CC so an early oty should be a more or less guaranteed win. Easy (to 1 turn KO).
Kenosis: You can't eat chargers without SoPa or eating a creature of your own first. Either he quanta locks you down early or loses. Usually the former but I wouldn't advise skipping him since the outcome is usually clear by a handful of turns in. Hard, easy to 1 turn KO.
Kichomo: Batshit insane damage but fortunately lacks CC. Outcome largely depends on how fast you can get otys and a meatshield SoFo up. Medium, easy to 1 turn KO.
Loki: Can't use BH before SoFoing sancs, can't really use SoFos before eating thugs and you pretty much need a SoPa to eat thugs. Can't eat Shtrigas until they act which is nasty. Medium, easy to 1 turn KO.
Lycaon: Potentially insane damage, nightmare, antimatter, ricos, you name it. Fortunately doesn't mind giving you tons of quanta with shadling + inertia though. Hard, with AM you either 1 turn KO him or you lose (see antiaverage).
Matrix: Pretty much guaranteed to rush you before you can do anything. Ludicrously hard.
Neysa: Lacks damage, lacks CC, lacks pretty much everything. Sancs make quanta locking a PITA though. Easy (to 1 turn KO).
Nirrti: If you can't quanta lock him (which is hard because he has tons of time quanta) before he pops neurotoxin you're pretty much guaranteed to lose unless you have a purify in hand. Hard, time barrier makes 1 turn KO hard as well.
Nosferatu: Unpredictable, can throw almost anything or pretty much nothing at you. At least you can eat most of his stuff without a SoPa and quantum towers mean lots of delicious HP from black holes. Easy-Medium, inadvisable to 1 turn KO as he's loaded with wings.
Pele: Nasty rush potential and packs RTs. Medium-Hard, burrowed graboids will also interrupt your brawl (sometimes a good thing) which makes 1 turn KO hard but you can probably still get waiter.
Perses: If he gets an early pulvy and a crusader grabs it the game's pretty much over right there. Even if he doesn't wardens can delay you long enough it makes no difference. Medium-Hard, attempt neither a 1 turn KO nor waiter (unless he's quanta locked) or you'll just get blocked by debris barricades.
Sesha: Plenty of fodder for your otys and delicious rainbows for black holes. Easy (to 1 turn KO).
Suwako: It's pretty much a race on who gets the druid/oty out first, although his aether income is rather low so you might be able to stop his CC with nymphs and black holes. Druids are wimpy so brawl can help too. Medium, easy to 1 turn KO but make sure you can eat his phase shield in need.
Swamp: Tons of damage you can't recover from, shrooms are largely inedible for your otys and so many pests your otys couldn't keep up if they tried to. Hard.
Tempest: He can deck you out both through stormspike and innovation, unimpressive apart from that. Easy as long as you don't attempt a 1 turn KO, unless he's quanta locked of course.
Thetis: Squids freeze you, puffer fish are too big for your otys right off the bat and poisonous too. Hard, easy to 1 turn KO.
Tatatitat: Sooner or later he'll get a flying titan out, overdrive it and that's game over right there. Harrrrrrd.
Definitely: Matrix, Swamp, Thetis, Tatatitat.
Almost definitely: Lycaon, Nirrti.
Maybe: Antiaverage.
Only if you aren't on a streak: Anubis, Halwn, Kichomo, Loki, Perses.
Some Dgs (Kenosis, Pele) are quite hard but since you can usually determine the outcome of the game 2-3 turns in I wouldn't skip them on turn 0 as they're easy 1 turn KOs.
OUEI: 2.66
WR: 62.00%
Games: 50
Time: 104.79
3,Halwn,W,36,106034,100,100,288,01719,30,1,0
3,Perses,W,49,165311,100,100,412,0177f,180,2,0.1
3,Anubis,L,24,83207,-23,100,-20,-,0,0,0
3,Sesha,W,28,82609,100,100,332,017dr,30,1,0
3,Matrix,L,9,29240,-16,100,-20,-,0,0,0
3,Higgs,W,25,74466,100,100,332,017dq,30,1,0
3,Pele,W,42,182959,100,100,412,0177h,8.25,2,0.1
3,Pele,L,15,50848,-1,100,-20,-,0,0,0
3,Perses,W,45,124420,100,100,310,0177f,180,1,0
3,Neysa,W,47,106136,100,100,436,017n2,8.25,2,0.1
3,Perses,L,20,64566,40,100,-20,-,0,0,0
3,Akan,W,37,96173,100,100,442,017do,30,1,0
3,Suwako,W,47,136979,100,100,484,0180d,30,2,0.1
3,Gobannus,W,30,77938,100,100,344,017tb,180,3,0.2
3,Perses,W,51,134481,100,100,540,0174p,30,4,0.3
3,Thetis,L,13,45774,-2,100,-20,-,0,0,0
3,Hydrax,L,52,138382,100,100,-20,-,0,0,0
3,Sesha,W,36,128100,100,100,442,017dr,30,1,0
3,Perses,L,54,189176,100,100,-20,-,0,0,0
3,Atomsk,W,34,100537,100,100,310,017t5,30,1,0
3,Tatatitat,L,11,55400,4,100,-20,-,0,0,0
3,Cardinal,W,51,164141,100,100,442,017qm,8.25,1,0
3,Kenosis,W,49,124629,100,100,532,017jv,8.25,2,0.1
3,Bernoulli,L,13,25432,-2,100,-20,-,0,0,0
3,Bernoulli,W,50,121964,100,100,442,017ni,8.25,1,0
3,Tempest,L,44,111852,100,100,-20,-,0,0,0
3,Matrix,L,12,28064,-8,100,-20,-,0,0,0
3,Higgs,W,41,121234,100,100,398,017n6,30,1,0
3,Kichomo,W,50,161707,100,100,484,017dm,8.25,2,0.1
3,Swamp,L,9,26647,37,75,-20,-,0,0,0
3,Anubis,W,44,167044,100,100,354,017t7,8.25,1,0
3,Kenosis,L,11,16137,26,100,-20,-,0,0,0
3,Tempest,W,39,142017,83,100,292,017t6,30,1,0
3,Kichomo,W,44,124901,100,100,388,017di,30,2,0.1
3,Cardinal,W,49,156729,100,100,578,016u5,180,3,0.2
3,Matrix,L,11,33160,-5,100,-20,-,0,0,0
3,Anubis,W,33,153951,100,100,354,0171l,30,1,0
3,Nosferatu,W,27,53754,100,100,364,017aq,8.25,2,0.1
3,Atomsk,W,49,149916,100,100,578,017t5,30,3,0.2
3,Tatatitat,L,13,43722,-18,100,-20,-,0,0,0
3,Atomsk,W,50,133086,100,100,442,017tb,180,1,0
3,Kichomo,L,12,32840,-46,100,-20,-,0,0,0
3,Thetis,L,24,90116,-4,100,-20,-,0,0,0
3,Loki,W,49,166691,100,100,486,017u0,8.25,1,0
3,Antiaverage,W,49,179264,100,100,412,016u5,180,2,0.1
3,Bernoulli,W,52,141261,100,100,526,017n0,30,3,0.2
3,Matrix,L,11,27211,-2,100,-20,-,0,0,0
3,Higgs,W,34,156033,86,100,274,017h2,30,1,0
3,Neysa,W,52,154845,100,100,532,017n2,8.25,2,0.1
3,Lycaon,L,19,58569,-7,100,-20,-,0,0,0