Most and Least Useful Thief?

[dem]

Most: Lookout or Cleaner

Least: Locksmith

I know it really varies from level to level, but what would be your pick for playing a level, and your last choice?

[Differ3nce]

The funny thing is that this completely flips as soon as you get to a higher level. The lookout is almost useless, since you don't need the skill to see guards and the cleaner is hard to use in later levels as he makes too much noise cleaning people. The locksmith is the most useful for speedrunning, because he opens everything really quick.

Personally I play with every character, but I play least with redhead.

[madhaha]

It depends heavily on the level and the skill of those you play with. For example a bad Mole can quickly doom your entire team by drawing unwanted attention, destroying cover etc. Bad lookouts think their job is to stay rooted in one place and don't help you scout ahead or collect coins.

I disagree entirely with Differ3nce on the poor late game performance of Lookout and Cleaner. Cleaner comes into his own because he can greatly simplify the game on the crowded later levels. The noise is not an issue unless you need to clean 4-5 people in a row. Lookout helps you see coin placement and lets you know when you can ignore security measures/run around because there aren't any shooting guards nearby.

Locksmith is useful in reducing safe cracking time but most of the later levels have C4, wrenches and now rocket launchers. Redhead can be faster getting through locked doors.

Most situational: Mole, Locksmith, Hacker

[Differ3nce]

The cleaner has been buffed and he has improved by that. So yeah, he's much better on later levels now. The lookout is useful if you want to speedrun in groups, since you want to know where all the coins are and she's also a bit faster than the other characters. If you do not speedrun, I think you don't need her, because you can see the footsteps if guards get close. But for a 4 player game she can really help out.

[dem]

How has the cleaner been buffed?

[Differ3nce]

The amount of agro he produced when cleaning was reduced, i think.

[AndyN.]

We reverted the changes because he was too good. He is the same as he always is now.

[Thinkaman]

This is such a cop-out, but it's a function of level of play, single- vs. multi-player, goal, level design, and preference. (In that order imo.)

For example, the Locksmith and Pickpocket are beastly at low level play, unimpressive at mid-level player, and extremely good at high level play. Cleaner and Mole are amazing at low level play but get outshined in single-player as the play masters the game.

At "highest" level play? Based on campaign levels?
-The Locksmith is really good, probably second best character.
-The Lookout is potent but niche in single-player, and really good in multi-player.
-The Pickpocket is objectively speaking the best character, full stop.
-The Cleaner is the second-worst single player character, but pretty solid in multi-player.
-The Mole is gimmick and meh in single-player (level-dependent), but also pretty solid in multi-player.
-The Gentleman performs poorly but is the most reliable character. It's really hard for a skilled player to make mistakes as the Gent.
-The Hacker is probably the "worst" character, though not by much. (He's definitely viable.)
-The Redhead is similar to the Gentleman, but is more versatile, difficult to utilize, and better in multiplayer.
-The current Blonde (last I saw) would be the worst character if she counted. I totally agree with the dev prediction that simple numerical tuning could make her way better.

Playing the game single player Lookout is imo the best way to master the game. Also playing Pearls Before Swine with each character; imo it's the most balanced, ideal map? Nguyen's finest hour!

[MonkeyPocket]

Pickpocket doesn't do well against jewelry tho ;)
I think that Lookout is in the Top 5 thieves, overall. It is particularly useful for relatively new players, otherwise they stumble across guards, when playing a map they don't yet know.