16. Which RPG do you enjoy using as-is?
Hmm. This is a harder question than which RPG I tinker with, which is a lot of them (in small ways). Again, it feels like cheating to say FATE, because that game is designed as a powerful and flexible toolkit that is intended to be adapted to whatever subject you're playing, and it includes explicit assistance to help you do it.
It also feels like cheating to answer using a vanilla ruleset like CALL OF CTHULHU uses, despite the fact I've been playing it (and by "it", I mean the 5th edition rules, from the early 90s) with virtually no changes for a long, long time.
A lot of "indie" games would work, but to be honest I've read a lot more of them than I've played. FIASCO is a masterpiece of simple, focused design that does exactly what it needs to and doesn't require any tinkering.
I'm probably overthinking, but I feel like the spirit of the question is "which game has flavourful mechanics that you like as-is", and I guess the answer that springs to mind is SAVAGE WORLDS.
Sure, SAVAGE WORLDS is swingy, combat-centric, and you really have to be in the mood for a RPG that emphasizes the "game" part, but if that's your groove it's a heck of a lot of fun. The "exploding" die mechanics are super fun, and it does a great job of stripping a traditional RPG down into the smallest possible space.
I don't know what it would be like playing a SW game long-term, but for a one-shot where there are a lot of baddies to be whomped on, it's pretty much in my sweet spot.