i had a 2 player panel with a 6 button fighter layout, two u360s and a trackball, on a horizontal monitor. this was set up to run everything, with minimal controls.
i have since set up a showcase cabinet as a 4 player machine, players 1 and 2 have u360s and 6 buttons, players 3 and 4 have JLWs in 8way mode, and 4 buttons each, this is with a 27" horizontal monitor. i am going to setup my other cabinet with a vertical monitor, a single 4way, 3 buttons and a trackball, and have it configured only for vertical classics. (pacman, donkey kong, frogger, dig dug, centipede, millipede, etc). about 30 games in all. those are the games that I play the most, however the kids that come to play, and my kids generally enjoy the games which are playable on the other cabinet. there are lots of vertial games that use 8way sticks, but i can play them on the 4player cabinet.
it really depends on what you want. i love the classic 4way games, so i naturally want a cabinet set up to play them with the best possible controls