I don't think the options for a wide angle APS-C prime shooter are very good at all.

Number of wide-to-normal angle fast primes made for Canon APS-C: 1 Sigma, zero additional if you include adapters.
Number of wide-to-normal angle fast primes made for Canon full frame: dozens of Canon, half-dozen Sigma, and *hundreds* of others if you include adapters.

So on the one hand you have the Sigma 30mm f/1.4 and on the other you have dozens or hundreds of options. I really think your best option is to upgrade to full frame. If you want to shoot fast and wide/normal primes, it's really the only option. If you want to shoot narrow f-numbers at wide angle, then APS-C is fine. If you want to shoot wide f-numbers at telephoto, then APS-C is fine. It's only when you want to combine the two that APS-C becomes a significant limitation. And here's why:

Making wide angle SLR lenses is expensive. There are downsides. When you buy a fast wide angle full-frame lens and then don't use it as a wide angle, but a normal, you are getting the worst of both worlds. You get the low quality and/or high expense of a fast wide-angle, without the benefit of actually being wide angle.

If you set out to make a "normal" lens for APS-C (35mm), you can make it fast (f/1.8), sharp, *and* cheap. Like the Nikon 35mm f/1.8 for just $200. You can do the same thing for full frame, like the EF 50mm f/1.8 for $120 (which goes a little too far on the "cheap" side of things when it comes to mechanics, but stop it down to f/2.8 and it's sharp as a tack).

Of course, Canon could copy Nikon and come out with an EF-S 35mm f/1.8 that is sharp and cheap. Or maybe one that is more around $500 and *really* nice. But they haven't, so there isn't really any *good* choice -- just a bunch of mediocre ones.

The good news is that plenty of original 5D bodies are still ticking away, and the 5D3 release should only push their value that much lower.