Cheap multiFX are comparable to cheap single pedals, expensive multiFX are comparable to expensive pedals.

A plasticy Zoom is probably the equivalent of some of those nasty Dod stompboxes, or the Dano minis. The Boss GT-6 is at least the equivalent of the Boss stompbox range. An Eventide Orville is probably better at what it does than anything you'll find in a pedal.

A lot of people don't like multiFX because of either the presets, or because they can't get the hang of, or don't like, programming sounds. If you're not willing to learn to use the thing, it'll never sound good.

MultiFX offer much more flexibility in terms of changing sounds rapidly; just changing patch could turn 3 FX on, 2 off, change the parameters on another 2 and change the order of the FX blocks. Doing that with pedals would be pretty much impossible.