I really like the way Fallout Tactics did it. You had individual turn-based, where each actor on the field got a turn. Squad turn-based where your guys all shared one turn, then the bad guys took one turn. And continuous turn-based which was like real-time, but spending action points to perform well, actions.

Individual was annoying because the one guy you needed to have a turn would somehow ALWAYS end up going after everyone else and was occasionally the last one standing.

Squad was better because you could co-ordinate the group.

CTB was harder. The AI seemed to cheat more than was strictly necessary, having occasionally perfect reflexes when they shouldn't have any chance of shooting back.