Cwmcarn is great – you can do both trails in a single sitting if you want, but if the two I prefer Twrch if you don’t want to go mad. There’s a uplift most weekend that’s will take you up the DH or to the top of the Twrch for a second-lap etc.
Afan is different, more old-school, tighter, rockier.
W2 is (as you probably know) Whites and The Wall combined. Either is good. Blade decided opinion a proper marmite trail. W2 is a safer bet. Penhydd is a bit rubbish these days IMHO, the surface has suffered a lot in places due to the trees going – it’s not rocky, it’s jus my rough and batters your hands at any sort of speed.
BPW is brilliant, start in the blues and work up to it.
Bare in mind your current plan calls for 80k+ of tough climbs and rough trails before you get to BPW, personally that would be more than I’d fancy before a day at BPW.
I’d ride Twrch on day 1, The Wall or Whites day 2 and save some legs and hands for BPW.