I've seen some reviewers (Drew Brad in particular) say that the magnets in the bell tips are too strong.
I like both these pyraminxes and agree with other comments - the Moyu is faster, looser, and the magnetic feel is more subtle.
Bear in mind though - you can adjust the strength of the magnets in the Bell! Qiyi has a video online - there are inserts to move the edge magnets further away IIRC correctly, and you can (if I remember right) take magnets out of the tips to make them less strong.
Incidentally, Drew Brad's said in his pre-nats video that he spring swapped his Moyu Pyraminx and put in Bell magnets - he didn't remember what springs he used and I asked on the forum but no one seems to be sure - if anyone knows I'd love to find out.
Both are great pyraminxes, I don't think you can go wrong between them.
Everything that
@chron0s say is right and great.
I myself have just done some changes and what not on both my Moyu magnetic and X-Man Bell and both are much better then they were.
Here is what I have done to them:
1. I have spring swapped both of them (one to the other), and they both feel much better, especially the Moyu Magnetic. I used to not like the Moyu and I have not used it almost at all before I swapped the springs, but now I am using it a lot and I really like it. The Moyu turns so good and smoothly now and I honestly have nothing else to say about it, other then that I really like it and it is one of the best feeling Pyraminxs I have ever tried. So if you want to try adding X-Man Bell springs to the Moyu, I would highly, recommend it and I do not think that you will be disappointed at all. Additionally, I would not be suprised if that is what Drew Brads did to his Pyraminx
2.For the X-Man Bell, I added the Moyu springs (as I said above), as well as took out 1 magnet from each tip.
Now, for the feel of the tips, they are weaker then they were before (and I think that some people might want to take out 2 magnets for a much weaker feel), but I like the click as it is now (which is definitely noticeable but not as strong as they were before).
For the Moyu springs in the X-man, I will say for starters that they are shorter then the one that were already in it, so as I am sure you know you will need to tighten the Pyraminx quite a bit to get it stable and with out popping. But with that being said, once you tighten it and add a little lube, the Pyraminx is wonderful and I like it much better then before. As I said with the Moyu Pyraminx, I do not think that you will go wrong with doing what I have done to mine (at least try it out and see what you think).
Final thoughts: I really really like both of the Pyraminx's now and I am rally glad that I tried out what I did, because now I use both of them a lot (meaning both are my mains), and they are honestly some of the best Pyraminx's I have ever tried.