I have a Grizzly 14" (G0555P) that does the job for me. In all honesty I think it is perfect for everything I do with it.
That being said, if I had the funds for a 17" a few years ago when I made my purchase I would have gone for the 17". From everything I've researched the 17s are a bit easier on on blades, especially the 3/4s blades that I use for rip sawing.
If you're thinking you're going to be ripping thick pieces of timber (12" or more) then you might want to consider going to the higher HP on the 14", but for the price you might be better served just to jump to the 17"
My two cents.