So, for a while I fought the idea of spending a lot of cash on L glass, not because I didn't think it was worth it, but because I figured I should learn how to use my camera first, so that I wouldn't waste the quality on poor technique.
Well, I think I'm at the precipice of not being a complete and total moron with the camera so I'm starting to do some research.
My usual go-to lens is my 18-135mm, it's got a decent f/3.5 when wide open, and it's got IS, which is nice. I'm pretty happy overall with the sharpness, especially stopped down and above 24mm, but it's not the best glass in the world obviously.
My other kit is the T2i body, the 75-300mm f/4-5.6 (non-IS, non-USM), and a Nifty 50mm.
So, I figured I can sell the 18-135mm (it's in 'like new' condition, I have the instructions, but I bought it white box, so I'm not sure how much I could get for it, I'm hoping $250 to $300, especially if I toss in the hood and UV filter) and get either the:
a) Canon 24-70mm f/2.8L, Mk. I, for $1600. This lens has great reviews for being sharp, it's fast at 2.8, it doesn't have IS, but the fast aperture hopefully makes up for that. I don't think losing the 70-135mm range is much trouble, since the 75-300 covers that about as well (to be honest, I'm not thrilled with the performance of either lens in that range, but I tend to shoot pretty nearby and wide)
b) Sigma 24-70mm f/2.8, for $825. This lens also has good reviews, not quite as good as the Canon, but my coworker swears by it. He claims it is similarly high optical quality, not quite as much build quality. Same comments about the focal range as option A. I'm a little iffy about buying non-Canon lenses, and it seems too good to be true for it to be comparable to a lens that is nearly twice the cost. Again, this one is not stabilized, but fast aperture hopefully compensates.
c) Canon 24-105mm f/4L, for $925. This lens has good reviews, not quite as good as the Canon 24-70mm, but good. It is not as fast at f/4, but it has IS, which may be more valuable to me, since I tend to do a lot of my shooting in bright sunlight, or on a tripod with a timer. The extra reach is more convenient, as is the price admittedly.
I'm torn between those three, so help me out, give me some advice? Please ask any other questions that might help my decision!