Is The Sims 3 a GOTY contender?

No, it is a very good game in itself, but it won't get any GOTY awards. It's a darkhorse candidate at best.

IMO yes.

Nah, I don't think so. It was a pretty good game but there are certainly dozens of others that trump it in my mind.

I'd imagine it's one of the bigger sellers of the year, but I don't know if they improved enough on the second in the series for it to garner a GotY award. 
 
If you're asking purely on a personal level, then no, The Sims 3 is not a GotY contender in my eyes.

I have it, but for my kids and frankly, they don't play it a hell of a lot.  I wouldn't think so, although I would rather play Sims 3 than Modern Warfare 2 or Unchartered 2 any day.