BDK has the best toy in all of pinball with the crane. I seriously hope that it gets incorporated into other games in the future. However, sadly, the rest of BDK I think is really not that great. I like fast games, and it has a surprising amount of stop and go. I actually really want to try the "lite" version of this game, as it appears to fix all of that to me and I think looks awesome.
X-Men is a surprisingly awesome game I think, it just needs to get past the code issues that people seem to still believe that it has. As it stands, it is a very solid package, and although it doesn't have a single toy as cool as the crane - to be fair, I don't think any other pinball does - it seems to be the better overall package.
If you can get a chance to try them both, do!