I'm sort of with Faceplant on this one, I remember their Street Fighter II ports being quite horrible and the controls being quite unresponsive. I know you can easily beat the opponent by spamming moves but that doesn't make the games any more fun in all fairness because there's next to no strategy. I'm not going to act like Hummer Team's fighting games aren't the best either (although to be fair there's not a lot of competition in terms of NES fighting games) but even their games did require some strategy with the AI.
...however, after looking through Cony's games, I have noticed they did make an attempt to improve. Some of their non-Street Fighter II related games (Fatal Fury 2, World Heroes 2, Mortal Kombat II) seemed to have more responsive controls. Hell, I think their composer improved a bit even though their sound engine doesn't really do them well. (while they aren't perfect, I do like some of the tracks in Fatal Fury 2 and the new tracks in Super Blaster VII Turbo 28 even though they aren't perfect). The AI (except for Mortal Kombat II) is still spammy as hell though and the engine is still not perfect (like the fact you can't block certain moves) so even then, the games are still pretty crap. Mortal Kombat II seems like the best of their games because the controls are responsive and unlike Hummer Team's Mortal Kombat port, this actually plays much more closely to the original game. Once you get the controls down it's not too bad. (Hell, the AI is actually tolerable) Yet, the overall presentation is probably the worst of Cony's games and to be fair, it still lacks quite a bit from the original game when compared to Hummer's port. (Although don't play the Mortal Kombat V1996 Turbo 30 Peoples version, it's a slower, glitchier version from what I remember)
So yeah honestly, I think Cony's pretty much the bottom of the barrel when it comes to NES fighting games (and hell maybe just NES bootleg games in general). There's only like one game I can think of that can be considered decent and that's really about it.