Hello! I'm Jeff Findley and I've been around since alt.toys.lego was first created, which is centuries ago in Internet time.
My favorite Lego theme is Space. My first real space set was the Galaxy Explorer and I've never stopped since. I also have just about every space related Town set (i.e. the space shuttle sets).
My wife's favorite Lego theme is Trains. Her collection is all 9V trains.
The oldest two kids have a few sets (mostly Bionicle and Harry Potter), but they're teenagers and seem to be in their Lego Dark Ages right now.
My youngest daughter loves the new farm sets as well as anything Town. Her favorite thing to build is houses.
Our family's collection also contains absolutely huge amounts of plain bricks that we picked up in the Lego Buckets over the years on sale after Christmas. Some of those were more than 75% off. Those sorts of deals are few and far between these days, which is a bit sad.