Out of this generation, 21 is the only album that can compared to Thriller, and really only because of its commercial success. TD is more comparable to Bad, for obvious reasons.
I actually prefer The Fame Monster over Thriller. I dont think Thriller is anything special besides a few classic songs that were HUGE but even then, I'm not a huge fan of them.
If anything It's better. If released at the same time as Thriller TFM would have beaten it to the top of the charts. Thriller was overhyped. The Bad Romance video is better than the Thriller video.