Plant burgers are only so-so, their target market are the meat eaters looking to reduce their meat intake including the "meatless mondays" crowd; many vegans are repulsed by premise.
5 Guys burgers and fries are fantastic, for "fast casual" I prefer Shake Shack and Umami Burger which is closer to a sit down restaurant than it is to fast casual. If you want a thicker patty, try a burger at mid-tier chain steakhouses, Ruth Chris, Flemings, Capt Grille, etc. Some locations have them during happy hour along with cheaper drinks. All produce burgers better than 99% of the burgers out there.