One of the fun things about being in aviation is the endless, pointless "this versus that" debates that take up a lot of time without any resolution.
Champ versus Cub. "If I wanted to drive from the backseat I'd be my wife," was the best line I ever heard during one of these. And yes, I concur.
Trikes versus Tailwheels. "Real pilots fly taildraggers" sounds really impressive until one understands it's being told to a DC-10 pilot that has a zillion zillion hours. I don't actually take sides in this too much, though I've only ever ground looped a tricycle geared aircraft (long story).
Certified versus Uncertified engines. Hooboy, always a good'un, as it crosses the Production vs. Homebuilt divide. Both sides have great points and a fistfull of statistics behind them to support their views along with loads of stories. The subsets are the two stroke versus four and the auto-conversion versus decertified engine debates.
Invariably the words "cheap," "dinosaur," "reckless," and "obsolete" are going to be used. Bonus points if the Wright Brothers, Curtiss, or Rutan are referenced.
What others have I missed?