There are some great answers here:
Tim C. is a good bassist, but in my opinion is outshined by Tom Morello's guitar. As you said, they are a good pair, and definitely sound better together than individually.
Les Claypool has a great vibe and makes Primus.
Flea...his style has varied greatly, but he never seems to get rusty. Great slap, but can be very fluid and melodic as well. Incredible live show on all parts - though I'm not the biggest RHCP fan, I think that they are, together and individually, some of the greatest talents of today.
D'arcy...can't say that I'm a fan. Cool rock chick, seems to have a great time, but...I just don't feel her.
Honestly, it's hard to choose a favorite bassist, because mood affects preferences. I love Flea for his versatility, but I have a huge soft spot in my heart for Geezer Butler. The intro solo to NIB alone makes me (and every other bassist I know) tingle with glee, even having heard it time and again.