Something with a proper sized seatpost. I got a mk1 Soul (mostly because I had one back in the day) and everything was fine except for bloody 27.2 seatposts and crappy droppers.
That Slackline looks like an awesome buy but will it be OK with your fork? IIRC pre-X Anthems were 80mm standard and Xs 100, maybe you can change the length but I think the Stanton was designed for 140mm.
(I have a 130mm or 140mm maybe QR TALAS 32 somewhere you can have for peanuts, out of that Soul, but tbf it wasn’t very good in 2010. TBH I’m sure loads of stw people have random old revs and sektors and pikes that we can’t bear to part with even though they’re worth 10p.)