I think there seems to be a consensus on the overrated guitars. So I'll cut to the chase and concentrate on the underrated ones...
1. Gretsch Duo Jet
Without a doubt the most comfortable guitar I own. I actually own two Jets. An Elliot Easton sig model with Filtertrons (like the one in the photo) and a Silver Jet with Dynas. There's something to be said about "that great Gretsch sound", but my EE Jet can also rock the house if need be. When I got my first Duo Jet, I dumped my Les Paul. Haven't owned one since. If you've never played a Gretsch Jet, you don't know what you're missing.
2. Epiphone Dot
Known as the "poor man's 335" the Epi Dot is a pretty reasonable facsimile thereof and has got to be the best bang for the buck going. Nice fit and finish, pretty solid electronics (as Asian imports go) and a nice 335-ish tone. If you don't want to shell out the cash for the real deal, you really can't go wrong with the Dot.
3. Squier Pro Tone Series
These Korean built Squiers were so good, Fender killed the line after only two years because they were eating into the sales of Fenders. They simply blew away anything Mexican-built, and many felt they were just as good as the US made guitars for less than half of the price. Ash bodies, high quality hardware and pickups, beautiful finishes and appointments...what wasn't to like? I own two Pro Tone guitars (the two pictured below). Although I do own another USA Telecaster, I only have one Strat and this is it. Five other US Strats have come and gone, but not one could touch the Pro Tone in terms of sound and comfort. You can find these on eBay usually for under 400 bucks. If you see one, by all means, grab it!
4. Fender JagStang
A collaboration between Kurt Cobain and Fender brought forth this odd looking, but nonetheless cool design that was a refreshing break from the endless variations on the Strat/Tele theme that we've come to expect from Fender. Surprisingly comfortable for a short-scaler, it also had its own unique sound, which was far enough away from the Strat and Tele to make it worth owning. I used to own one and now regret having gotten rid of it. Definitely worth checking out if you see a used one hanging in the shop.
5. Charvel Surfcaster 12
Back in the late '80s and early '90s, if you wanted jangle but couldn't afford a Rickenbacker, the Japanese-built Charvel Surfcaster was the affordable alternative. A semi-hollow design with a really comfy neck, plenty of jangle, great build quality (as we'd come to expect from the Japanese by then) and a really cool look made this one of the best bargains around. After Akai bought Jackson/Charvel, the semi-hollow Surfcaster was axed from the lineup. These neat guitars command such high prices nowadays, you can pretty much just go out and buy a Rickenbacker straight away. If I had known how much these guitars would be worth today, I wouldn't have sold mine back in 2002. But for me, the Surfcaster 12 was sort of the "gateway drug" to Rickenbackers. The money I got from its sale went toward a new Mapleglo 330/12.
6. Robin Ranger
How does a Robin Ranger sound? Think: Tele Custom on steroids. The Rio Grande pickups can be punchy, twangy or sparkly, and the workmanship of the guitar is nothing short of excellent. With the Ranger, you'll be able to handle pretty much anything from Keef to Waylon...and look good doing it.
BTW, with regard to everyone's slamming on Ovation guitars...I own an mid-90's USA-built Ovation Elite and it's one of the most beautiful sounding acoustics I've ever owned. Dunno, maybe I was just lucky and got a good one.