I LOVE my Handiquilter Sweet Sixteen sitdown. I've never used a LA though. There's something about a LA and how it rolls and not being able to be anywhere in any movement that doesn't seem to make it through my skull LOL. But with a sitdown you can quilt any direction you want and there are no rollers, so no boundaries. I also tend to like to turn my quilt to quilt in certain directions (I just don't think well upside down or backward).
I do a lot of ruler work now...I didn't in the beginning. But I have gotten better with practice. But prior to that I was doing FMQ on my domestic sewing machine.
I highly recommend it!