Nikon 14-24 F2.8 or bust, for drains and cranes anyway. My Nikon 28-300 is a great all around lens too, but it's more for natural light type stuff. I really need to stop being a cheap-ass and pick up the 24-70 f2.8 one of these days though. And a 85 1.4 as well, those things are hot ;D

50mm, plain and simple.

I like my simple cheap 35mm f/1.8 DX nikkor. really sharp pics. been looking into the Tokina 11-20 pro

I own a Pentax K30

Pentax has really good lens, especially their limited primes. But it does not offer as wide of a lens selection as Nikon or Canon. This is where Sigma came in handy for me.

Although it is not always the best overall lens to use, I really love using my Sigma 8-16mm f/4.5-5.6 . It is not a fast lens, but since i tend to use a tripod most of the time this is a non-issue for me. It has a ridiculously wide field of view with minimal distortion. Perfect for caving, tight areas such as bunkers or just fit an entire room inside the frame.

My pentax 18-135mm is my work horse, and i also have several fast primes for special occasions.

Ive been using the Canon 10-20mm wide angle for most of my shots. I wish it gave you more than 3.5, but it does the job. I just recently picked up the nifty fifty 1.8 by canon. For the price, you cant beat em!

Nikon 35mm 1.8ED G (quite a mouthful) on my D750 is pretty much my go to. I'd love a nice ultra-wide prime though, something like a 20mm maybe or a 16mm. However, those cost and arm and a leg...and probably your other limbs too.

I love the nikon 24mm PCE lens and I really want the 19mm

I'm going to cast another vote for the Tokina 11-16. Absolutely gorgeous to shoot with. Just wish I owned one of my own so I didn't have to borrow it every time

Tamron 17-55 for walkaround
Sigma 30 1.4 art for inside prime
Canon 85 1.8 for outside prime
Wide: I got rid of the Canon 10-18mm. Great lens, super quiet, light and cheap but for inside shots (real-estate and UE) you'll get green ghosts of lights or windows repeated in dark rooms.
Using a Craigslist Sigma 10-20 as a replacement. Just as sharp, no green reflections. But heavy.