Both? Either?
The game I am thinking about GMing (and GMing to me is play, just a slightly different kind), regardless of setting, will use 3F. It will almost certainly not be fantasy.
If you want a fantasy game, or a game using your various dice system, run it. Obviously I can't run your system and I have no intention of running a fantasy game in the foreseeable future.
It appears you have a clear idea of what you want to play (and/or GM). That's great, it's more than I can say, I have little more than a vague notion of fists (and legs, nearly as frequently) in the air. Rebellion, resistance and revolution seem to be where my head's at (can't imagine why).
What I do know is that running a game featuring magic, elves and the rest of the usual fantasy tropes has no appeal for me at the moment. Playing in BBB will cover my need for fantasy.
If thaf kind of fantasy appeal to you: go, do that. I will root for it to be a success, enjoy kind of following along if it happens where I can see it, but it doesn't interest me enough to invest in playing it.
It was the same with Izzy's Cortex game - it took a turn that didn't appeal, so I opted out. Some very cool stuff was shaping up, but it was a thing I didn't really connect with. Dresden Files is the same; people love it but I'm pretty meh on it. Y'all go, Harry Dresden it up if that's your thing. I'll sit on the couch and watch for a minute, but I'm probably going to go shoot pool at the first commercial.