So my B-Day is coming soon, and I figured I was going to buy a lens for myself because I have been nice all year. Anyways, after quite a bit of research I have lowered down my options to three fixed focal lenses: Sigma 15 mm f2.8 diagonal fisheye. Pentax DA 21mm f3.2 limited. Tamron 90mm f2.8 macro. Those lenses are probably all going to make it to my bag eventually, but I am wondering which one I should purchase first. So far, the Sigma looks like it is going to be the one because I have found a pretty sweet deal on a used one. But it is a fisheye and considering my current lineup, is it smart to purchase a specialty lens? The Pentax is a beautiful little lens, and it would be a great walk around lens, but it is pretty close to my 28mm prime, so there is no rush for that focal length. And for the tamron, it could be used for macro, moderate telephoto, and for portrait, but it's a focal length I am not too familiar with, and as I do mostly cityscape pictures, I don't know If i would use it much... So what would you guys do if you were in my shoes? Does anyone have some experience with one of those lenses and can recommend or advise me against any of these? Thank in advance you for your time and advices!