I find myself coming back to speed gel a lot, so it's probably my favorite. I have only one released map that uses funnels, and I don't think I like them much. This may be because I used them a lot in my early (crappy) work and got burnt out.

EDIT: Geometry overkill maps are also something I don't really like. However, lasers CAN be used in other kinds of puzzles, which can be fun

Now lasers, those are just terrible. Thinking up a puzzle with lasers that doesnt degenerate into a university-level geometry problem is just ludicrously difficult.

also panels. they are simple to make and make the map look so much more professional

Pete wrote:
Now lasers, those are just terrible. Thinking up a puzzle with lasers that doesnt degenerate into a university-level geometry problem is just ludicrously difficult.

This is, for me, a massive issue; at heart, I'm a mathematician, and I find it very difficult soeties to remember that other people might not be. Hence, I have an excessive love for laser puzzles.

I absolutely hate an overdose of Turrets. (I made a map like that once and it wasn't the greatest)

I love Portal 1 styled chambers, you know chambers that involve little to absolutely no use of the new elements, it brings back the feel that made me begin to love Portal in the first place.

Least favorite: lasers. I actually like Valve's use of the Thermal Discouragement Beam, but there's lasers done Valve's way, and then there's lasers done any other way. Valve is smart to limit lasers to a non-central role in most puzzles they're a part of, and keeping what few laser-focused puzzles they have extremely simple (e.g. Triple Laser, which is near the end of GLaDOS' chambers but is incredibly simple compared to other chambers in that portion of the game).

There's something alluring about using the laser in a map that I've never been able to place, but it's hard to design a laser puzzle that is hard enough to require some thought and trigger an "Aha!" moment, but easy and short enough that the player doesn't end up getting tired of the puzzle before it ends. I've been playing with my own laser puzzle designs for a while, but have yet to find one that finds that balance and is fun enough to polish up for release. :\

Fizzlers and panels have a surprising amount of potential, but aren't commonly thought of as elements on their own.

I'm in between on lasers, but I think their annoying side is overused in certain maps. I loathe when a map just drops you in a room full of relays where you have to make the laser go through multiple portals, back through the portal at odd angles, or any sort of weird trial and error. But I think they can be great when used as part of larger puzzle, where you don't have to go through hoops to activate something, but you think about how you can use it to your advantage. I'm aiming for that goal in a map I'm currently working on.

I haven't had a good bond with gels really, but I like them all the same.

Man, portals. Remember them?

As for puzzle elements I do like ... well, cubes are OK, I guess.

Overall I just think they could have been better implemented.

I do also want to sing the praises of light bridges, which are probably tied for first place on my list. They're pretty versatile, which makes them great fun to work with. Walk on them, use them as a shield, use them to block a cube or player, use them to hold a cube or player in place, use them as ramps. They also combine really well with gels.