If you could buy one ...

[Picsfor]

You didn't include the Nikon 12-24 :'(
The only lens Canon don't make that i want... :'(

 

[jcns]

I own 2 out of the 3
24-70 L 2.8
35L 1.4
50 1.4 (although looking to upgrade to L 1.2)
50D user

They are all very good lenses, but serve vastly different purposes.
For walking around 24-70 is the best in my opinion. You can make it work in indoor sports; I took some HS basketball shots (HS gym) and it was fine. I am assuming you have the technique.
35 L 1.4 is fantastic for very low light indoors; last weekend I took shots of a band in a bar. Great Great Great. This lens is a bit short for outdoor shooting in my opinion; I find myself walking up to things much more than I would like. When shooting street scene, I prefer to keep a distance.
50 1.4 is great for night street scene shooting; it's just too long for indoor shooting such as parties in a house.

 

[jm345]

Of the 3 lenses for the OP's stated use "wide variety, including portrait, landscape, interior, and even a little basketball" I would recommend the 24-70L as providing enough to satisfy those needs more than the other two lenses. Having said that, I just sold my 24-70L because I tend to use the 24-105L IS more because of the IS. If Canon comes out with a 24-70L II with IS, internal focus and as sharp as the 70-200f/2.8L II IS I would buy it in a heart beat.

 

[wickidwombat]

out of those choices for me it would be the 50 f1.2L for sure, I'm not a fan of the 24-70

 

[bycostello]

all depends what you are shooting, but the 24-70 purely for versatility... do you really need f1.4?