1. Canon 70-200 f/4L IQ is stunning in every way. I still get better results (IQ) with this then my 85mm f/1.8 (except below f/4 ). I wish I could use this lens all the time! (Maybe more when I eventually upgrade to the IS version). I like the light weight also. Wished the AF worked better in really low light, but I guess that's the limitation of f/4
2. (I have it quite yet!!) Sigma 30mm f/1.4 I borrowed this from my friend for a week. It was glued on my 30D the whole time. I fell in love with it right away. Such natural looking pics, this is what 50mm is suppose to look like (on FF) after all!
3. Sigma 24-60 f/2.8 I paid $220US brand new off Amazon, can't beat that. It's been my "work horse" lens for 2 years now. It's "ok sharp" wide open, but f/4 and up it's as sharp as any other lens I've used in this range. The AF is kinda slow and noisy, but it's pretty acurate and doesn't hunt too much. If and when I get the Tamron 17-50VC or Canon 17-55IS, I will keep this as my trusty backup (which can work on FF in the future!)
4. Canon 85mm f/1.8 This is the first prime lens to impress me (ok.. the only other i've owned is the nifty). IQ is amazing, It practically works in the dark.
5. Sigma 10-20 very fun lens to use. When the sky is blue it's really makes great pics. I use this hand-held in churches as well. I see no reason to upgrade to Canon or Tokina for the price.
6. Canon 18-55 IS I never owned the original non-IS version to compare, but this this a very good lens for a kit lens. The IS works pretty good and IQ is pleasing. I only sold it because I needed money for other things.
7. LEAST FAVORITE Canon 50mm f/1.8 I've had 2 copies in the past, just sold the second one last month. Soft, crappy AF, crappy build quality. Maybe I had 2 bad copies, maybe it's just a crappy lens. $100 you get what you pay for...(of course the 18-55IS is worth about the same, but much better lens IMO)