I don't expect anybody to have seen both series yet. I'm not through FUBAR yet but I have seen Tulsa King. I'll reserve opinion until I finish FUBAR's first series, and we can all vote as and when we've seen both.

I think it's an interesting battle seeing as though it's Arnie vs Sly but in the TV world; both of their first real forays into scripted TV. They've done bits before but these two series' feel like them both jumping with both feet into that sphere, and almost at the same time too.

I've only seen 5 episodes of Tulsa King and have yet to start Fubar.
Eventually I will finish both just haven't been motivated enough lately

So I finished FUBAR and I've got to say that I very much enjoyed it. Arnold has the unique ability and confidence to bring levity to action and just make it work, a la True Lies, even at his age now. I also found the series un-formulaic but still as if produced by network TV, if that makes sense. I would have groaned if at the end but none of that happened, which to me was a tick.

As for the thread question, I honestly like them both but decided to go for Tulsa King just because it's Sly and prefer him. But both shows are solid outings for these ageing action superstars, so there's comfort in that.