Well, we need to keep in mind that nobody would have been a "perfect" fit for all fans, and that anyone replacing Portnoy would be offputting for some. But on balance, I felt and the time, and still do feel, that Mangini was by far the best choice out there. Of the others who auditioned:
-Donati: I think he would have fit in just fine. He knows and likes the music, he can play it both in terms of being faithful to the originals AND in terms of bringing his own style and deviating from the originals. And from what I can tell as an outsider, it didn't seem like there would be any chemistry issues.
-Lang: Definitely had the chops. His personality is a bit quirky and different, but I didn't necessarily see it as an obstacle. He is musically very literate and seems like he could write and jam the way they like to. Seems like it could have worked. It seems like this gig was not exactly what he was looking for, but it also seems like if he got it, he would have taken it, and it appears he and the band could have adapted to one another easily enough.
-Minneman: Definitely has the drumming and musical chops. But I'm not sure he fit in personality-wise, and based on his own comments, I don't get the impression he would have been committed to remaining with them long-term. So I don't see him working.
-Roddy: Has some GREAT drumming chops. But doesn't appear to be a good fit and doesn't appear to have wanted it. And by his own admission, he was not comfortable writing and jamming the way the band prefers. With great respect for him, I have to say that he was not a great fit for the band. Not to slag his playing at all. It just wouldn't have been a good fit.
-Wildoer: This is an interesting one. He is most known for playing in a different style. But he knows and appreciates DT's music, and showed that he can play it faithfully. The chemistry also seems to have been good. If he would have been willing to relocate to the U.S., I could see this as working, even though it may have felt quite different to the fans for awhile. I don't know that he would have been as easily accepted, since he is not a big name and not known in the genre.
-Priester: I unfairly bashed the suggestion of him even being one of the drummers prior to the reveal. But his playing and his attitude impressed me quite a bit. Despite that the way the video was edited, and it gave the impression that he couldn't quite nail The Dance of Eternity, I think he could absolutely play that and fit in musically. He has the playing chops. And his overall attitude and humble personality are really refreshing. But I'm not sure he would have been a good fit either in terms of chemistry and writing.
I wish we could have seen Bobby J. audition as well. I have no idea whether he would be a good fit for the band. But he absolutely has the drumming chops to play the music, and I LOVE his drumming style.