This thread is great/funny: Sunday River? hahahahahah
I've really only gotten to ski the Loaf consistently, so I can't vouch for any lines elsewhere. That said, I think Sugarloaf is great (but probably not the best). There aren't any cut cliffs on actual trails like there are at other resorts, nothing really gnar and cleared 100%. Nitro, Gondi, and the FF snowfields are awesome and long as fuck, great terrain in that sense. Woods are fun as hell too, there's some great stuff in brackett and above it (hells gate, backside, etc). Gladed cliffs are decent, I've explored some crazy shit on Burnt that hopefully can be hit next year.