I much prefer the sound of a good condenser mic. If using in a bedroom studio use the most directional polar pattern the mic has (cardioid, hyper-cardioid)
Try using the mics high-pass filter if it has one.

SM58s are ok, much better for live use and recording guitar in my opinion. They are not as sensitive and are highly directional.

In either case if you havn't got a good pre-amp they will both sound crap anyway.

Also a pop shield or wind sheild is a must for getting rid of plosives, without one you will have to use different mic placement techniques which will result in more noise, less bass etc etc.

Also watch out for the proximity effect.