I currently own only Canon lenses though I have owned a few third party lenses in the past with mixed results. I had a Sigma 10-20mm which was very good and I'd probably still have it if it worked with my full frame cameras. Also from Sigma was a 300mm F2.8. At the time it was acceptably sharp but the focus was a little slow.
My 17-40 f4 is probably my least used lens but when I do it is excellent. Great colour and contrast and is very sharp.
For general everyday use my most used lens is the 24-105L f4 IS. Again, colour and contrast are good but sharpness is a little lacking for an L series lens. I also had the common problem of the aperture control cable breaking inside the lens. Canon's service dept. soon fixed it albeit at a price!
My favourite lens is the brilliant 70-200 f2.8 IS. I've taken tens of thousands of photos with it and it's superb. Now that mkii version is out and it's supposedly even better, I daren't go and try one as I know I'll end up buying one!
Update: Well, the inevitable happened. I was in a dealers shop in London with my camera gear and asked if I could borrow the Mkii lens to try in comparison to my earlier lens. I took a series of shots at different apertures focusing on buildings quite a long way away, as this is how most of the time it will be used in aerial photography. Once I got home and opened up the images in Lightroom it became obvious that the new lens was sharper everywhere and especially in the corners. I ordered one the same day!
Starting at the widest, I have the 28mm f2.8. It is a great little lens with good colour and contrast and is very sharp even wide open.
My next is the fantastic 'Nifty Fifty' 50mm f1.8. It is the cheapest lens that Canon sell and it is one of the sharpest. If the Canon 50mm f1.4 is used at f1.8, the 1.8 lens out performs it. When you consider that you can buy 4 of the f1.8's for the price of one f1.4 it's a no-brainer... unless you tend to throw your gear about as the f1.8 does (I'm told) suffer damage quite easily. I'm very light on handling my gear so it's been no problem to me so far.
The 100mm f2.8 macro is another lens I don't use that often but when I do it's brilliant. Colour and contrast are excellent and the sharpness is fantastic whether shooting something at life size or shooting aerials at infinity. The bokeh of this lens is also fantastic for portraits.
My longest lens is the little heard about 400L f5.6. This fantastic lens is a favourite with the birding community because it is very light, very sharp even wide open and the focus is lightning fast. I bought this lens after quite a lot of research to replace my truly awful 100-400L f5.6. This was soft at all apertures and focal lengths and every time you zoomed in it blew dust all over the sensor due to the poor design of the thing. The only good thing I have to say about that lens was I bought it very cheap and made a small profit when I sold it!
I have a mkii 1.4x converter that I occasionally use with the 400mm for wildlife and moon shots.