I like the possibility to get cheaper minis than GW:s. But anyone claiming Mantic, besides the occasional lucky shot, makes better minis than GW needs to get glasses. It is not about taste either, those human of them deserve to be recasted into something less ugly, like their ghouls. The design of their for example is beyond retarded.
I might consider sneaking in a few mantic elves among my elves as somekind of suicide Shadow warrior units whose job is to live hard and die young. The only army I could consider making solely out of Mantic minis is an undead force. At least all of those minis are passable. The rest is so bad it is not even worth paying for unless they like dump the price with half. At the very least.
Even if Mantic would be my only economical option to collect a fantasy army I would simply choose not to collect an army at all.