Which RPGs are the easiest for you to run?
This seems an odd question, I suspect it's asking if I prefer to run crunchy games, or if I prefer rules-lite systems. Maybe it's asking of I'm an OSR grognard or a hippy story-gamer.
Honestly, it doesn't matter much to me. There are types of games I don't particularly like to run... I don't particularly like railroading games that weave a specific narrative every time, which is probably why I never really got into many of the early Indie games. My GMing style tends toward giving the players a long leash, or maybe giving them plenty of rope to hang themselves by. Weaving logical ramifications to the actions undertaken by players through their characters.
If a game is "hard to run", I just ignore the hard parts, get stuck into the setting, focus on a few of the signature elements of the game, and in most cases, most players don't know the difference. They have a good time (or a gut-wrenching emotional time), and that's what's important to me in a game session.