Beta 58, 57, and 56 all use the same capsule are all supercardioid, similar to hypercardioid. You can check Shure'a website if you don't believe me. They're all much more directional than an SM58. I prefer SM57s over SM58s, Beta 58s over both, and Beta 57s over all of those.
If I was doing more singing on a regular basis I'd get either a Beta 56 or an Audix D4 and put it on a gooseneck. Low profile, sounds great, and finally, eat the mic like you've been backpacking for two weeks and just got back into civilization!