Ok-here's my advice. The best $600 acoustic you can buy is one that fits your hands, and is made well. It is often used, but if you are set on a new guitar- Anybody can pick a brand or model, we all have them. Mine for cheap is a Korean Breedlove-
http://www.musician.com/product/Breedlove-Atlas-Series-AD200SM-Acoustic-Guitar?sku=512406
Their movable bridges are revolutionary, and I generally prefer the work of Korean luthiers to Chinese or Taiwanese. I've seen some Indonesian dirt cheap Mitchells that are surprisingly good, and own one. The damn thing has perfect intonation, not a buzz in sight, is easy to play, and still manages to sound like a cheap guitar. The Breedloves I've played all managed to sound like a *real* guitar, and there goes about $350 extra.
The tough part is this, though. Remember the part about your hands. If microphones are like shoes, guitars are like gloves. It's all about scale and neck radius. My badass guitar and yours may be quite different. To further complicate matters, guitars are made by humans (mostly) out of wood (usually) , which are not uniform in nature. The cheaper guitars (and most other things) are, the worse the quality control is. Looking for a cheap guitar, I have played as many as 16 of the same make and model, trying to find one that didn't have something obviously wrong with it. The salesman loved me.
Anybody can find a good $5000 acoustic, if they have $5000. A good $100 guitar? You hit the jackpot. A good $500 guitar? You have to be careful. I advise avoiding mail order, and play the exact guitar you will own, and be satisfied with it. You sound like someone who would do well to go guitar shopping with a guitar-god buddy. Buy him lunch. He may find things wrong with guitars that you miss.
Finally- brands to look for in your pricerange? My favorites include : Washburn, Yamaha, Seagull, Takamine, Ibanez, Beedlove. I'm not a fan of current Epiphone acoustics, although some of the older ones rock. I also don't love the cheap offerings from the big names- Martin, Taylor. I love my Taylor, but in your pricerange, I think there are better guitars than the Big Baby. There are bizzillions of other brands, including vintage models-Harmony, Hagstrom. I'm not a big fan of round-back plastic hybrid guitars (Ovation, Applause), but there are some that don't totally suck, so playing them is worthwile. You need a strap, though, 'cause they slide down your leg.
Any of the guitars listed above (and no doubt, countless others) could be that one that nobody screwed up. Generally in that pricerange, you don't get the top tonewood, so when looking for a mid-priced acoustic, I focus less on tone, and more on playability and intonation. At least get one that was made well. Then you have a guitar you can play enough to get good at it, then buy a higher priced axe. Then "Old Faithful" becomes the camping and dangerous duty axe. Good for biker bars. It fits *your* hand, has a good stable neck with no buzzes, is easy to play, and doesn't sound bad.. Good luck-Richie