It's usually both due to my tastes. Growing up with the Spectrum, Gameboy and some late 80s/early 90s PC games, alongside the Wonderboy series and Streets of Rage 2 (major influences), I'm drawn to games with RPG mechanics and home computer/console arcade/action games as well as anything a bit different. Take platformers - re-releases aside, games like Crash and Spyro on the PS1 are 'collectible' (which seems to be a euphemism for 'worth a bit' to most people) despite not being rare at all. Genres like survival horror tend to have limited copies produced, so again are 'rare' and 'collectible' despite being the games I actually want to play.