Definitely try 25 Burgers!
I've passed the one in Bound Brook a million times, but thought it was just some lame and greasy burger joint. But this past weekend FI and I happened to pass the one in Linden and decided to try it out... OH MY GOD, I have a new food obsession. They're the BEST burgers and fries I've ever had. The burgers were cooked perfectly (not soaked in grease at all), the sweet potato fries and honey mustard were the best I've ever had, and the chili cheese fries were delicious!
FI said he's passed the one in Linden a lot and it's always packed, but we happened to go on Sunday night and it was empty. The guy who helped us was really friendly (he threw in drinks for free because we said we were first-timers and he said he guaranteed we'd be back) and the interior of the building has a slightly retro feel to it. We preferred taking our food to go, but there were a few tables and a counter to sit at.
I'm assuming both of their current locations (Linden and Bound Brook) have the same menus and they're supposed to be opening one up in Westfield soon. Definitely stop by if you get a chance.
http://www.25gourmetburgers.com/index.htm