I've been playing PnP RPGs since 1975 (good old D&D in the white box) and since many of my friends are also into RPGs (probably why they're friends, similar interests) we've tried many, if not most, of the PnP RPGs available at one point or another.
It's not so much about the rulesets (tho character agency is VITAL to an RPG) but setting.
Different genre's, different combat systems (sword & sorcery combat vs battlemechs vs 20th century), different core concepts (personal wealth & fame, save the universe, survive & prosper), etc. All add interesting "twists" to the character centric game-play fundamentals.
And I could go on for hours about instances where I and other players did things based solely on our characters perspective of right/wrong normal/abnormal that in-real-life we'd never do,