Here's my list of the most useful. Apart from αPat's CE at #1, it's in no particular order.
- αPat's CE. I think it's really in a league of its own. Most other CEs are simply part of a character's toolkit, but what's so nasty about αPat's is that even without it, αPat has everything he needs to be competitive. When added on top of that, it serves as the perfect tiebreaker in the close situations that are intrinsic to the highest levels of play. It's like how the house always wins on draws in blackjack.
- Viola's CE. Gives three risk-free mixups. First mixup gives a combo if the opponent guesses wrong. Second one gives heavy mixups if the opponent guesses wrong. Third one gives slight frame advantage if the opponent guesses wrong. Basically another free tiebreaker CE, but arguably riskier to apply than αPat's.
- Cervantes' CE. Similar reasoning to αPat's. Pros are that it's extremely fast, has infinite range, and is a big part of his combo game. Cons are that it's high and does comparatively low damage (except in combos).
- Patroklos' CE. i13. 90 damage. Rings out. Always has meter for it. Annoying to punish for some characters. Frame traps after many of Pat's moves. Tracks to one side (which is useful despite 66G; people like to attack out of sidestep, and this can catch that).
Honorable mentions:
- Pyrrha Ω's CE. i13. 90 damage. Good range. Combos off a lot of stuff. Tracks both sides slightly. No real downsides.
- Ezio's CE. i13. 90 damage. Decent range. Good clean hit chance for 110+ damage.
- Astaroth's CE. Big coin toss. Damage ranges from heavy to hilarious.
Crap CEs:
- Aeon's CE. The worst. Crap damage, slower than most (i14), whiffs, unsafe on hit against some characters. It's his fastest forward RO attack though, so it can be used to punish -14/-15 for ringouts when the opponent is positioned appropriately.
- Algol's CE. Unlike Aeon's, it's not a bad CE, but it's mostly a gimmick. The meter cost/damage ratio for his BEs is better and he can use them off almost all of the same moves that combo into CE. His CE can be used for super long range whiff punishes (which can lead to ringouts), but the opponent has to be whiffing at long range in the first place, which isn't likely to happen if he knows the matchup. Again, gimmicky.
Hilde, Leixia, Maxi, Mitsurugi, Pyrrha, Raphael, Tira, Voldo, Z.W.E.I., Yoshimitsu, and Siegfried form the middle class of CEs. They're not incredible, but they fit with the characters well and have their applications. They're nicely balanced between impact time, damage, and combo ability.
When it comes to certain CEs (Astaroth, Ivy, Nightmare, Dampierre, Xiba), I don't think these can be as easily placed. When we talk about how "good" a move is, we're intuitively estimating its
expected risk/reward over a large number of repetitions, but when it comes to the typical time scales we see in SCV (FT3s), I'm not sure if this is a very good measure. CEs are used relatively rarely as is due to the meter restriction, and these 5 CEs in particular are pretty much all or nothing in their risk/reward, which makes it more difficult to rank them.