i'm going to have to say opening bell is my pick. you can't beat the atmosphere- a coffee shop where you can actually spend the afternoon in a book undisturbed. and free internet! just understand that since the espresso and such isn't automatic, it does take a few minutes to get your freshly brewed drink. i've heard the place get's really busy for the shows at night so i look forward to checking that out sometime. you can't get more homegrown than this place
Drip - To me, the coffee here is good, but not great. The drip coffee can be bitter, and espresso is usually pretty good. Their baked goods, from doughmonkey, are nearly unrivaled. Any non-brit scone fan would love theirs. great atmosphere. It's clean and modern.
Urban Dog - I had some really good espresso here and sampled the coffee. I've only been there once. The sitting area isn't as nice, but anyone with pets would love it, as it's also a pet supply store.
Zaguan - Not really a coffee shop, but they do all the requisite drinks. My drip coffee wasn't great, but they probably don't make enough to have a regular turnover, so who knows how old it was. Their desserts are wonderful.
Opening Bell - Decent espresso. Great atmosphere. They support a lot of local music at nights. It appears that tuesdays are open mic, so you might avoid that, unless teens who name their bands before they write songs are your sort of scene.
Corner Market - There maybe multiples of these, I'm not sure. I was on lower Greenville. Downright bad espresso. I will admit it was decaf and i watched as the "barista" used a pod to make it. They have a grinder so I assume that regular will be better. Still, who would charge coffeehouse prices for a pre ground pod? for shame.