I've tried all of them except for legion (got the game for Christmas, just barely unlocked him), so far i like northstar and scorch. Ronin is too much cqc for me, haven't gotten a good hold on tone or ion. Sniping titans and pilots is a lot of fun, and scorch's area control is absolutely hilarious. Pretty much stonewalled a trio of enemy titans last game i played, got a triple with my flame core. (Luck of course, not much skill there.)