I choose bad. My reason being is that most of them were used pretty badly.
This is my opinion of RCs in the future of the KH series.
[begin rant]
RCs were generally fairly cool, to look at, but not often used right. Some of them did make perfect sense, such as the ones for Shadow Stalker and Dark Thorn or Xemnas, but most of them fell flat/ were pointless. Part of the reason for this was KH2's difficulty level already being easy. Most of the time, the game was easy as is. All the RCs did was make an easy game even easier.
One solution for that problem would be make the next game that uses them (such as KH3) harder, but I don't believe that solves the issue. I think the biggest pitfall was that they were too easy to activate. A fair amount of the more predictable ones could just as easily be done by taping triangle repeatedly until they come up. So, what to do about that? How about consequences? By this, I'm talking about the possibility of the RC working against you. Suppose you start mashing that triangle button in anticipation of the upcoming RC.. Now, instead of the chance of simply missing it, how about you make it work against you by doing this. In other words, tapping triangle too early isn't exactly going to hurt you too bad, but if you start hitting it repeatedly, instead of possibly giving Sora the upper hand, it gives the boss the upper hand.
Do you see what I'm getting at? I'm talking about the boss getting his/ her own little "RC," should you decide to mash triangle, in anticipation for the RC. For tougher bosses (like Mr. Sephiroth) or higher difficulties, this could be made more stringent, to the point that simply hitting the RC button too early activates their "RC attack," damaging the crap out of you or just generally creating another annoyance. Actually, I'd love to see a wide variety of RC timing. RCs timing that's not just based on the difficulty setting, but the boss as well. (i.e. Tougher bosses give you less leeway than easier ones, or certain, special RC-based (but not necessarily hard) bosses judge your RC timing and not your button mashing skills.
Another option would be mapping RCs to more than just one button and/ or different locations in the combat menu, ala Luxord's/ Gambler's (I think) tricks. In the first case, it'd be say.. defensive RCs = square, offensive = triangle, and square = counter attack RCs, which you use not only to defend against the enemy's awesome attacks, but to turn it against them, hence it being a counter-attack and not just being Defense/ Offense. The second would be much like it has been.
In conclusion, though I didn't exactly like them as well as others, I'd personally like to see a RC revamp.. and a harder KH3.[/rant]