Actually, yes. There are 2 more players that shown their incredible strength in the past in the name of Ribannah and DaveMcW. But for some reason they don't play HoF and GOTM games anymore.
I think there are more, too, but i think they dont have any interest in submitting and de facto don't play GotMs. im curious how a few HoF guys would do in GotM but they dont play these, presumably for real life stuff but also to not need to prove who is best.
for the original poster, i think half the game is going to be undoing preconceived notions of the game. Let's Plays with commentary are the best source, imo. Even just playing the game will have you develop habits that aren't beneficial because there are subtle details that separate the best from the good players.
tommynt said that following some plans isn't as good as adjusting to the game situations. that is definitely correct but you would also need an incredibly thorough knowledge of every game mechanic. basically, learning all the strengths of each civ, settings, victory condition, difficulty, units, terrain, diplomacy, combat, etc. will be what defines you as good or not. if you are just now getting into this game you will need a LARGE amount of knowledge to really grasp how to be good at Civ5. it isnt the kind of game with a turn-by-turn "best" format approach for each game. this also may be a detriment to the game being "fun" if it takes a college-level degree to master this game. some people do math problems for fun and others hate it. Civ5 is definitely a large set of math problems at the really good player levels, imo.