I run what I consider the best all around size for a guy who would like to use a big sandblaster cabinet or paint a car but will rarely if ever need that much air. I use mine all the time! One thing I would get and not stray away from is oiled, they will last longer and be quieter. Also like said above get the highest scfm @ 90 psi you can afford.
Mine is a 230V, 60 gallon, V-Twin, Oiled, belt driven (with cooling fan), 18.1 scfm @ 90psi, Campbell & Hausfeld.
Campbell is a great brand, I have a factory 5 year warranty with this thing and so far its running strong. Its the "Maxus" brand of Campbell so its there lower cost model with the same parts....dont ask me why its cheaper? Its about 6' tall and at the widest point its 2' which is the cage around the cooling fan and belt. Depth from front to back is about 1.5' total. It has a nice sight window for quick reference of oil level and cleanliness. That's about all I have, I would recommend at least going to a local compressor shop if you have one, that's where I got mine. Sorry for my long rant.