I've rented the 24 f/1.4, and it's amazing. I haven't really done detail checks at the corners vs center, etc, but it's got amazing bokeh, especially when you have something close. Good detail, I'd say pretty sharp, but didn't really look closely at it. Nice and quiet with fast USM focusing, and not too heavy.
Haven't tried the 50 f/1.4 yet, although it's on my list to buy (replace the 50 f/1.8 I have). 85 f/1.8 I love as well. Classic portraiture length, and pretty large aperture. Great value for the money in my book, even if supposedly it isn't as good as the 85 f/1.2.
I rented the 70-200 f/2.8 IS USM II, amazing lens, pretty darn heavy, but awesome. However, I decided to spend my money otherwise. Specifically on the 135 f/2. Great lens, really awesome. I highly recommend it. About the same length & weight as the 24-105, but gorgeous bokeh at that focal length and wide open aperture.