Trouble Deciding...Wide angle purchase

I'm trying to decide how to expand my glass collection...and I have a few things in mind. Originally I was going to try and get a telephoto of 300mm or so but I've since decided that that's pretty impractical for regular shooting and I'd probably end up only using it for AutoX pics (not worth it). Now I'm thinking of going in the oposite direction. Here's what I'm thinking of:

Sigma 10-20mm f/4-5.6 ($450)
Sigma 17-70mm f/2.8-4.5 ($350)
Canon 20mm f/2.8 ($400)
Tokina 12-24mm f/4 ($450)

What I like about the 17-70 is that it would make a nice replacement lens for the kit: its f/2.8 (at 17mm), it has more range than the kit, (and is the cheapest option). I really like the pics coming out of the 10-20mm but its the most expensive option and its not nearly as versitile as the 17-70. I've also looked at the Canon 20mm prime (I almost bought one on ebay today but I held back). I don't know much about it other than its a prime wide angle so it should be pretty sharp. F/2.8 would make it pretty fast too. I also don't really know anything about the Tokina...just throwing it out there.

What do people think about these lenses? Are there any others I should seriously consider? This will probably be my last lens purchase for a long time (next couple of years probably). I'm a student and I don't have a ton of money to throw arround...but I just got payed and its burning a hole in my pocket! Anyway, see my sig for my current setup.

(Or should I spend my paycheck on a banjo and keep what I have?)

Considering the range of choices you have there, I'd say "Go with the banjo" :{)#

What do you find the kit and the 50 not doing for you? Are you always pushing one end or the other of the kit lens? Needing more light than you've got? Figure out what you need to do, then look for a lens that will let you.

Yep, the main thing is I need more light. Like to take indoor/night pictures but I'd really like something wide angle. I don't really have any qualms with the kit other than it doesn't let in enough light. The extra focal length from the 17-70 would also be nice. So would the fact that its a macro...(if you can't tell, thats the direction I'm leaning).

Maybe I should buy a nice flash instead of upgrading my glass? Would a 430ex be a better investment than the added benifit from the 17-70 Sigma?

Do you feel like you need to go wider than the kit lens?
If you do I would go for either the Siggy 10-20 or the Toki 12-24. Both are excellent lenses.
if you feel that the kit lens is wide enough, then I would go for the Siggy 17-70. It is a nice wide angle to normal walkaround lens plus it has Macro feature.
I have seen and heard nothing but good things on the Siggy 17-70 eventhough I returned the one I got last week due to soft OOF result. but I think I got a dude copy.
You might also want to consider the Tammy 17-50. I found it a lot sharper than the Siggy 17-70

I'd say go for the Sig17-70 first.

The other lenses are a bit more specialised and probably wouldn't get used as much.

The Sig 17-70 is most versatile of your selection and produces very good images. Get it and then save for another lens in either the wide or telephoto range.

i'll go the for 17-70. it's the cheapest but it will offer you the most bang for your buck! i think you'll find the focal range more useful than your other options. for those other wide lens options, the range will be too short for you to use as a walkaround lens.

you'll find plenty of happy campers who own a 17-70, including myself. for the price, you just can't beat it!

Is there much noticable difference between the Siggy and the kit lens? Do you guys find the larger aperature and the longer FL useful?

Big difference. I own the Sigma 17-70mm and it is an excellent lens. I must have gotten a very good copy because I have not found it to be anything but crisp and sharp. Having the extra reach at th elong end of the lens is very nice. Some don't need or notice but I find that for a general purpose walkaround lens it is a killer!

Low light is a relative thing but the Sigma performs well in medium to low light.

I had the Sigma 17-70. Was a very nice lens. I sold it along with my 29-135 to help fund a 24-105. I then ended up getting a 10-22 for more room at the wide end. I do think the Sigma is a great deal for the money. I ended up selling mine on Ebay for $290 after about 2 months.

Adam

If you can find the bucks to do so I'd go with the Sigma 17-70 and a 430EX flash.

I would only advice NOT selecting the Canon 20mm f/2.8. If you need f/2.8 at 20mm, get Sigma 18-50mm f/2.8 or Tamron 17-50mm f/2.8 for a few dollars more. They are just as sharp (or sharper) than this Canon.

I agree with Luckie8. I have been studying all these lens and more. I thought long and hard about whether I would use/need the 10mm to 16mm range. I came down to the 17-70 or the Tamron 17-50. The thought of dealing with a bad copy bothered me. I went for the Tammy due to that and reported excellent sharpness plus having F2.8 throughout the entire focal range. Good luck making the decision.