Well, some mics work for some people and some don't. That's why people won't tell you which one is better. I have a C-3, and it is a very nice vocal mic. While it isn't my first choice, it's a mic I would try when a couple of others aren't right.
Yes, the C-1 is cardioid only, the C-3 is cardioid, omni, or figure 8. The polar patterns don't matter much for vocals, as I would usually use cardioid for that anyway. The multiple patterns do make the mic good for a bunch of other stuff, however, such as close mic'ing (omni)and MS (mid-side) mic'ing, where a figure 8 is needed. Frankly, if I was looking for Cardioid only on a budget, I'd probably buy a Marshall MXL V67B for $100, give or take. For a more versatile mic, I'd pick the C-3. For bigger bucks (about $500), I'd choose Rode NTK, a tube mic. It's cardioid only with no cool switches, but is an excellent vocal mic. I'm a big fan of B.L.U.E. Dragonfly, about $800.
The bitch of it is, singers and mics are like pieces of a jigsaw puzzle. No matter how good the mic is, it'll sound like shit on some singers, and some songs. For me, if it was just for vocals, I'd get an NTK and never look back. However, for more general studio work, I'd choose a more transparent, multipolar FET mic, and the C-3 is a pretty good choice. Best of luck.-Richie