Get the Grizzly 10x22. It will be more costly overall but you will be much happier with it in the long term.
The smaller 8x14 and 9x20 are very capable machines and I am amazed at the work that I see many users produce with them. I started with a smaller machine and always found I was pushing it's limits. After much searching and fussing I bought a machine of similar size to the Grizzly 10x22 ( a Busy Bee Craftex B2227L 10x18 lathe) and I have never regretted it - only that I didn't go it sooner.
The Grizzly 10x22 is a well regarded machine and there is at least one reasonably active Yahoo group on the subject.
cheers, Graham near Ottawa Canada