I've tried the following...
D'Addario Chromes - These have steel wraps. They sound great, but I had to give my truss rod almost a full 3/4 turn clockwise over the course of 4 or 5 days to compensate for the high tension. Some people dig playing high-tension power lines for strings. I hate it. They feel like they have no give and take to me and after about 30 minutes of playing I took them off and threw them away.
Thomastik-Infeld JF344 Jazz Flats - These have nickel wraps. Sound amazing, but they're really spendy and I had to give my truss rod about a half turn counter-clockwise because of the low tension. This can not be understated... these are LOW tension flats (the A string is only a .070!!!). And that's why a lot of people love them. To me, they were maybe a little too low. I did keep these and I do want to try them again one of these days.
Sadowsky Light Guage Flats - These have steel wraps and are made by LaBella. Some people say they're identical to LaBella flats, even though Roger Sadowsky claims they're made to his "special" specifications or whatever... I have no idea... but, these seemed to be a pretty good balance between the TI Jazz Flats and the D'Addario Chromes as far as tone and tension goes. These stayed on my P-Bass the longest... 2 months... until I took them off and put on a set of DR Sunbeams and was able to smile again.
The Verdict: I spent almost $100 on flatwounds to come to the realization that I simply don't like them that much. When I hear other people playing them, I literally shit myself when I hear how good it sounds. When I play them... ehhh... not so much. They can sound really good if I spend time dialing in my amp... but I just hate how they feel. They have lots of bottom, and the steel flats especially have a nice "tic-tac" on the high-end, but they're lacking the throaty low-mid tones that I crave. The TI flats came the closest to having that tone, but... I still couldn't fall in love with them.