Usually a GM, rarely a player. I prefer science-fiction and modern/urban fantasy over medieval or high fantasy. At conventions, I end up playing and running lots of Dungeons & Dragons 5th Edition under Adventurers League rules.
- FanPro's Shadowrun (Played and run all versions before 6th Edition.)
- White Wolf's Changeling: The Dreaming (I own every book published in the original line. I also have the shiny 20th Anniversary edition, but I haven't used it.)
- Dream Pod 9's Silhouette (I run Robotech/Macross games, but DP9's Heavy Gear and Jovian Chronicles settings are fabulous, too.)
A Note on DM's Prerogative
It goes without stating that a DM can change whatever they'd like, so citing "DM's prerogative" makes any answer moot. The DM can always do whatever they like, so using it as justification just weakens an answer. Interpreting logic and word choice is a different matter.