I said other because I'll do a combination depending on the circumstance.
I usually just ask for separate checks at the beginning of the meal so no one is surprised at the end. It's easy enough for the wait staff to do if you ask for it at the beginning of the meal and saves any arguments over who should pay what. But with one friend we usually get stuff and share it, so we always just give the wait staff both our cards and ask to split it evenly. I have no problem doing that if for some reason the restaurant can't separate the check or if there's a lot of sharing involved.
I don't get my panties in a bunch over it. I mean, these are my friends. There will be times that I throw in a few dollars more, there are times when they'll throw in a few dollars more. Not a huge deal to me.
I have been out with people that like to split it to the penny (and don't ask for separate checks to start with) and that drives me crazy. I swear in every situation like that we've always come up a few dollars short. I'm usually the one throwing in more because it's not worth the argument to me.
If we're out with another couple and order an appetizer for everyone to share, I also usually ask for it to be put on my bill...I guess I'm generous?