I had a midarm and the other poster is right, you just end up wanting to do more. I have the 18" Avante as I stated before. I swore I'd never do large quilts, but guess what, I DO do big quilts. My frame is 14 feet. My shop is 7 1/2" by 17 feet. I get by, but would love bigger. I bought one roll of batting.................NEVER again until I get more room. The packages are so much easier -- plus, less waste. I know I can piece batting, but it's a pain. With packages I choose the size closest. If you buy 120" wide batting, even if you want to make a baby quilt, you have to cut the whole 120". I don't provide backing -- apparently some professional longarmers do.........I just buy what I need when I need....so far, out of 75 + quilts, I've only bought the backing on 4 for a special customer. She was unable to go out and buy. I like to match my backing to the quilt ---- so having 20 bolts of backing on hand is NOT feasible.
Oh -- another thought --- I know some people have the mistaken impression that you can adjust the frame for the size you want to do -- it's NOT easy to do that.............trust me. I've not seen a frame yet that you can adjust the size easily. I have not looked at the table top quilt machines, so maybe they adjust easily.