I started on earth day, of last year, and average 20 mi a day. I finally caved and built my own surly cross check, and have upgraded each part, piece by piece, and I perfect the ride as I go.
Ive learned a lot mechanically. My bike doesn't squeak, it gets a lot of comments, and I'm paranoid to lock it up anywhere except for my house or work. I just bought a cannondale p.o.s. to ride around town, as a result.
The difference i obsrve is explained by the 1987 jeep I owned and the brand new 2006 Subaru I bought. The Subaru starts every time. The 1987 cherokee worked... Most of the time.
Giant bikes seemed fine, and for commuting, really any brand will work. I recommend surly simply because of my enjoyment while riding it.