I've got an me-50 and I love it. I can get a variety of tones out of it, it's simple to use-no complex menus. Easy to tweek to dial in a sound, a wide variety of effects. The only downside I have with it, is the wah, it's real weak to me. But other than that I really like the me-50.
I have both multi-effects and to be honest I prefer the AX3000G. The quality of it's effects is a lot better and not as noisy as the Me-50. It also offers more functions. However, the only way to really find out is to try both of them in your local music store.