It is ultimately all about the $$ you are willing to spend. I agree with PaperPrincess that attending a show might be useful for you - firstly you will get to try out many machines, get lots of prices and perhaps one of the venders will have a deal on either a new machine or even a trade in that they have in stock. You can also check on Craigslist.
I started six years ago with this same search and ended up purchasing a used Voyager 17 from a fellow QB member not to far from me. The total cost was less than $4K. It was a perfect (for me) machine. It had a stitch regulator and a ruler base and worked perfectly. I quilted like mad on it and just sold it for less than $3k as I am now ready for something else. The gal who purchased my Voyager wanted to do her quilts from start to finish but had limited funds. So decent midarms are out there for a reasonable sum.
My new machine arrives Sunday!! My replacement for the Voyager is a new HQ Avante with a ProStitcher!!
Good luck with your search - take your time and do your research!!