I haven't seen an ABG (new) in the $300 range that's worth the money. Or, maybe a more friendly way to say that would be that they are all pretty much alike. At least those that I've had a chance to play, Fender, Ibenez, Honer. So if you don't want to risk a lot of money, check a few out and go with the one that seems well made and fits your hands.
Coming from a plank guitar, I'd recommend considering one of the thin-body styles over the more traditional dreadnaught guitar size. They are easier to manage and when amplified they sound fine. Washburn and Carvin both make thinner body ABGs. There are others. You might find one used.
Slightly more expensive ones are made by Godin, their "a4" also thin body, and the report on them is universally good.
Tacoma makes more traditional large-body style. Beautiful instruments but very pricey.
You're proably familar with the usual caveats: they don't have much volume unamplified and tend to feed back at high volume (though that seems to be less of an issue for most players). And if you amplify one, well, then you just have an electric, don't you? (though that is a bit oversimplified)
I've had a Washburn AB10 for years and am very happy with it. I don't need volume when unpluged. It's built like a Mac truck. I can (and do) practice any place. It sounds great unpluged and has enough range of tone when run through an amp. Light weight is a plus.
John