+1 on a Behringer dynamic. For vocals, the Behringer XM8500 is a great mic. It has a considerably higher output than an SM58 (so needs less gain at the mixer) and has better intelligibility. it's also "nearly" feedback-proof, within reason. It's a bargain at $20. I've used several of them for at least 5 years with no problems. Works great on a stand, but has some handling noise if you don't hold it still.
The Behringer SL85S was awful.
I just looked at the Roland Mobile Cube specs. It does not have an XLR mic input. It has what looks like a 1/4" unbalanced TS (Tip Sleeve) mic input. The above mic has a balanced XLR output which is Male. Most good mics are like this. With that amp, you would have to buy an XLRF to1/4" TS cable to use any balanced mic. The balanced mic would plug onto the XLRF end of the cable.
Otherwise, with the Cube, you will have to use some type of unbalanced mic with a TS cable, which would be (are) notorious for poor quality sound and very prone to feedback.
If you want to stay with Roland, they have the BA-330 which has the correct XLR inputs for mics, and 1/4"TS for instruments. Also, it can be mounted on a standard tripod speaker stand.
-W