Depends on what you're willing to spend. I have the Tokina 11-16 and its great. That being said its also $600 maybe less used. You could get the Tamron 17-50 2.8, but if you're looking for something wider i would get a Rokinon 8mm
. Its $300 on bh and im sure you could get it cheaper used. Before anyone says anything about how he said uwa, I KNOW that the rokinon is a fisheye, it will have distortion, just saying for a couple hundred its an option for something wide.
Confidence is the feeling you have before you fully understand the situation.