Dammit - I intended to do a poll who who supports whom - I suspect you'll be in a significant majority.
If I were a neutral, I'd probably support Saints, as A] Finished top of the league, B] TNT love-in with Bruce Craig and Finn Russell, C] They've played nicer rugby than Bath over the course of the season.
Against that, I think that Saints will win, which would usually push me towards supporting the underdogs.
If both teams get into their strides, there should be some awesome rugby to watch, and Saints favourites.
If it becomes a tight, scrappy affair with frankly too many basic errors, then Bath have more experience playing that way (not of winning them, necessarily, but playing scrappy with too many errors).
As a Bath fan, I'm happy just to be here - didn't expect to be at any stage in the season (pre-season I thought I was being optimistic thinking we'd get 4th-5th). I REALLY hope the players don't feel that way, but we've only one or two players who've done it before, whilst Saints have virtually a whole squad who've reached a final before.