I would say anything solid NOT made by Shimano, Daiwa, Megabass, or St. Croix, is underrated, lol...I own products from 3 of the 4 and they are all awesome, but it would be hard to argue any brand has the vocal following these have. Full disclaimer, when I'm looking for something "high end," I typically lean toward these brands along with a few others myself.
In all seriousness, on the low end, Berkley Cherrywood rods are very underrated...sure, the components are value driven and super basic, but they are rock solid and the rods are surprisingly well balanced and responsive for $25...seriously, $25...If your budget is tight, there really isn't an equivalent option in my opinion.
Okuma in general is underrated...I'm sure there are some stinkers in their lineup, but I haven't come across one yet. The Celilo rod (discontinued?) is one of my all time favorite light/ultra-light panfish/trout rods. The Epixor XT (I have the 40 size) blew me away for $50. Hell, even their big box store brand stuff like the Stratus V (I believe exclusive to Dick's) has impressed me at the price point. I picked one up on "sale" (although they never seemed to come OFF sale) for $25? $30? just to throw on an old pond hopper backup rod that needed a reel and I found myself reaching for that setup way more often than I imagined.
Pflueger...My favorite reel in my entire arsenal is the Patriarch XT baitcaster (I own 3 now). I love everything about it. It weighs nothing yet somehow manages to take abuse in stride, casts a mile, handles light(ish) lures well, brakes are phenomenal, and on and on...Pflueger does have their following, but most seem focused on their President spinning line. I admit the $250 price tag is steep, but you can find deals often and although I'll probably get heat for this, the honest truth is that I would STILL take the XT over a similarly priced Curado, Revo, or Tatula SV.
I find lower end Lew's (anything below the Tournament MB) to be overrated. There are plenty of Shimano/Daiwa guys that scoff at Lew's in general, which I strongly disagree with as I think the MB is one of the best all around reels on the market today under $200. They have plenty other rod and reel offerings above that $120ish price point that are also very good...However, I have been thoroughly unimpressed with anything below that level...I'd take a $70 Abu Black Max combo over the Mach 1 (rod AND reel).
St. Croix is overrated in my opinion...they make great products and remain an industry leader for a reason...very strong, very sensitive rods...however, I just don't find they balance as well as some other brands that get much less attention. I've only ever owned a Premier and I like it, but find myself reaching for other offerings more often. Mojo's seemed very heavy when handling in the store and although the Avids felt nice in hand, I just didn't think they were worth the price tag...maybe I would have felt differently fishing them.
My 2 cents...
Completely agree with the Daiwa RG-AB...love mine.