Isn't it so cool that the consumer has options? Anyway, this has been exhausted (a lot by yours truly) years ago.
If you want a simple sequencer with basic phrase and one-shot sampling, get a mpc.
If you want a workstation sampler with complete set of sample features and functions that are equal to software features found in hosts like Live, and samplers like Kontakt, incredible effects, tons of bells and whistles, and a very rock solid, fully featured midi sequencer, then get the MV-8000/8800.
Some people want more, some people want less. Get the one that works.
As to whether one is truly better than another, the answer is still yes, regardless of what a person needs. The MV is completely superior to the mpc (any version) in every possible way. An argument could have been made in the past about the mpc4k, but since that never worked properly, and has been abandoned, it is a moot point. This has been done in favor of cheapies like the 1k and the 500, and Akai's milking of the 2k, putting it out in slightly different ways over and over and over again for way more money than it is worth...
Everyone can take all that with as much or as little salt as they like, as I use neither anymore.