I have *played* neither brand, but Garrison is an interesting company. I got interested in finding an
acoustic guitar with the Buzz Feiten tuning system, and came across this brand. All of their guitars are made with a weird design: all of the bracing, kerfing, binding, bridgeplate, etc. is a single piece of "projection molded" glass fibre. The company says it makes the "whole guitar resonate" more efficiently. They did win a Golden Axe award from Harmony Central (if that means anything), and just about every model has the BF tuning (if you're into that--I'm still not convinced myself).
I guess the only downsides are that since most of the tough work is taken care of in molding, then the guitar is essentially made by robots and not real people; also, the guitar is not all wood. Of course, Ovation still has a good reputation with a lot of people, and their guitar bodies are mostly fiberglass.
On the good side, they have a lot of extras, a catchy gimmick, and are very reasonably priced. They are also made in Canada, so production standards I assume are pretty high (having played with Godin guitars now and then).
Like I said, though, I haven't played them. Playing a guitar is the best bet. I never buy a guitar before I play it.
Just my two cents...and by the way, the Garrison website is here if you haven't been to it already:
http://www.garrisonguitars.com