Now that we're caught back up, let's keep this train a rolling.
Which RPGs are the easiest for you to run?
Any RPG I'm incredibly familiar with that doesn't force me to reference a massive amount of charts to run. I really enjoy running FFG's Star Wars RPG because generally speaking I only have to look up Critical Injury results when someone scores a critical hit. Otherwise I generally don't have to look up most of the tables. I know by extensive practice what you can do with 3 Advantage, or 2 Threat. I know how much damage a blaster pistol does, or that a Vibro-Axe has the Vicious 3 quality. FFG even makes NPC management easier with their Adversary Deck. I've now got over a hundred adversaries on playing cards that I can dig through and slap onto the table as needed. The game system is so flexible that at a glance I can even add abilities and effects to the base card stats and my PCs are none the wiser. I theoretically COULD just sit down at a table with no prep-time or pre-made adventure and ask my players "okay, what do you do?", and generally speaking I could make up the adventure on-the-fly.
The harder RPGs to run are those that require a lot of chart-reference. Earthdawn comes to mind, as that game as a "Step" system that determines how many dice you roll. I got a lot of practice with that, but it's a lot harder to remember what you roll for Step 16, or Step 21, or 32. If a lot of bookkeeping is needed to play, that's a lot harder to keep up with while trying to keep the game going. Critters with massive amounts of hit points with a novel-length list of abilities can be very daunting to try and keep track of while you're trying to keep the action dynamic and exciting. You can totally kill your momentum by having to pause for 30 seconds while you figure out what a dragon or a beholder is going to do next.
I have a hunch tomorrow's question is going to be fun to write, and not in the way many folks are expecting. I anticipate that two or three of my friends will read it and have reactions like "...they WHAT?!"