I oftentimes run into players that are really impressive, though most of the time I forget who they are. The best.... might be tough to nail down. There are different things that I see a lot of players do that impress me. Some are really good at certain things and of course have their weaknesses. Some recent players of note for me have been:
Warlocks Barks and Faelqt: Barks has been fought to play against and Fael has been great to play with.
Phrontistery, Riptides, and Axia: Are my go-to shammy trainers. Goesid, is of course a wealth of information, though I've never seen him play being that he's an ocean away.
Izac: A master of timing cooldowns, sacrifice casting, and strategy.
Dradform: A master of jumps and FC ing.
Lennyw: Awesome at carrying tactics from what I've seen from his vids.
Deadvulcano/Livevulcano: A pain to play against, a valuable asset to play with.
Sekcmustard (Zarazsa?): Was crazy good back when I started in this bracket. Is he still around?
Duckyboy: Good FC. Smart use of positioning and Rocket belt in FR.
Felix, Lil, F2psiblings (Huntessin), Snug: Are great hunters that I've played with or against.
Bop and Oldspike: Though I've not played with or against them much (maybe ever?), I've gathered a ton of useful strategic info from them on here.
Snowjobs, Upswag: I've played with or against them when they are a variety of classes and they've been great at each.
"Them Ursin boys", HB, Kevi, Craycray, Xda, Phones, Layse, Patel, Persh, rhythmx, and others: Those that I have played with or against individually have been great, but most of all, their PVP strategies and the way they meld with communication is amazing to me.
Of course I'm sure I'm forgetting many people. Much of these stay in my head because I'm reminded of them here on TI. A lot of reputable players here on TI I haven't ever played with or against, but are probably excellent as well. I'll probably edit in some more as I think of them.