There really isn't a valid comparison between those two choices. I played TESO up to Veteran rank 6 and I've been bored to tears for quite some time now. I've easily spent 10x the time in Wildstar betas and I'm still looking forward to logging in come launch.
Here are some of the valid complaints I've seen about the game:
The classes in Wildstar lack depth: this is rectified somewhat at level 50 when you have all your AMP points and you can unlock the tier 8 abilities. It's still inexcusable that they couldn't have come up with more interesting skills throughout the leveling process as a significant number of people will not make it that far. It's not like they don't know how to do it (See: Stalkers).
The combat is boring: This really seems to be up to the eye of the beholder - some people really like the combat and others find it dull. Personally, with the exception of TERA, I've always found MMO combat to be rather lackluster. I certainly haven't found anything difficult in Wildstar outside of group/raid encounters but that's no different then every single MMO out there and I'm okay with that.
Wildstar is aimed at people who want to continue playing a game similar to WoW who aren't troubled by its lack of innovation. If you're looking for a game that's doing things differently - you're in entirely the wrong place. This is a game where the difficulty is in the raiding game, where you obtain +gooder items off bosses, and where your characters will progressively get bigger shoulder pads to highlight that they are internet dragon slaying bad-asses. If you're sick of that type of game, if you spend hours on message boards trying to come up with ways to advance to genre, or if don't enjoy slightly juvenile humor mixed in with 'the fun stuff is at the end game' then you will hate this game. If not, you'll probably enjoy Wildstar (but I'd recommend trying it first!)