Poll = Your Most and Least Favorite Areas in PoE!

Most- Ledge
Least - Imperial Gardens/Hedge maze

Most favourite: Crematorium.
I like those maps like catacombs/prison/crypt and so on.
TI feel the crematorium has a nice blend of enemies in it and the fight at the end really serves as a wake-up call to any characters that haven't payed much attention to their resistances.

Least favourite: Sceptre of God.
I was originally going to say the Imperial Gardens/Hedge Maze but then I remembered those leaping Chimerals from the Sceptre.
Oh, and Caliga.

Most - Ledge
Least - Imperial Gardens

Most: Catacombs: It has a high monster level relative to most zones in Act 3. Large size of the map and a reasonably open layout makes for a target-rich environment without a ton of latency. Map tends toward forming a big ring, so not as much backtracking as you might expect. Final room which guarantees yet another rare/blue monster encounter and good odds of a large chest. Corrupted areas attached to this zone are generally manageable. Good for leveling or magic-find. Except for the Undying, mobs have slow movement and attack rate, which is helpful for incomplete builds/less skillful players (like me!).

Least: Imperial Gardens: A maddening layout with multiple backtracks, dead ends and blocked-road detours, for some arcane reason this map is the hub for three other zones. Having the waypoint is less help than you might think. Annoying spawns of those juke-and-puke Avian Retches and spike-on-death Porcupines contribute to the pain. Devourers pop up with alarming regularity, and seemingly always in a choke-point you (think you) have to traverse. The proliferation of map obstacles might or might not block your spells, ranged attacks or movement skills - it seems to be a toss-up. The bare smattering of chests apparently only exist as triggers for statue spawns.

Most: Library (really really cool design)
Least: the area after brutus.... hate it.

Don't know why everyone is hating Imperial Gardens, pretty nice zone except for the quill on death dudes.

It's Hedge Maze which is terrible layout-wise. However:

Most: Fellshrine
Least: Sceptre of God (only god damn shitty monsters, wtf)

Most - LEDGE!!

Least - Scepter of God

Favorite: Catacombs
Least: Gardens.

Favorite: Church dungeon in Fellshrine. Amazes me noone's mentioned it - it's been my fave zone since closed beta. :)
Also really like Catacombs for the same reason; I just like to crawl dungeons I guess!

Least favorite: act 3, especially the act 3x stuff (Imperial and up to Dominus). That stuff is just terrible to me, I skip it on all characters and difficulties, and just run all the way from the Barracks up to Dominus whenever I'm equipped to deal with him. By far the least enjoyable content in the game I think. I did a full clear once when it was new, and it was exhausting and not the least fun.

From an aesthetic standpoint my favorite is barracks/battleftont. Least is the urban slums/warehouse/market areas(not the sewers).