I am a relatively new owner of a Handiquilter Sweet 16 sitdown machine, I really enjoy using it. There are no feed dogs so the sitdown machines are not exactly like a domestic machine with a larger throat area.
I found the stitch regulator to be cumbersome while FMQing but I like to use it when quilting with rulers. You can do an amazing stitch in the ditch with rulerwork.
I highly recommend taking classes - I overcame my "new machine fear" when I learned how to adjust my tension and how to use the accessories correctly.
Good luck on your search for the best machine for you!