I have seen every Mania since X-8, here is how I would rank them
1) WrestleMania 21 - So many great singles match up's: Rey/Eddie, HBK/Angle, Orton/Undertaker, Cena/JBL, HHH/Batista. It established MITB with still possibly the best MITB match yet. Plus I just loved both main event storylines going into Mania, they were so well done.
2) WrestleMania X-8 - Do I even have to say it? So many matches! So many good matches! This was my first Mania so I thought it was the greatest thing I have ever seen. Loved the Hardcore matches throughout the night. DDP WAS THERE. Hogan/Rock made that event infamous.
3) WrestleMania XIX - Like WM21, they had so many good singles match up's: Austin/Rock III, Hogan/Vince, Angle/Lesnar, HBK/Jericho. HBK vs. Jericho and Angle vs. Lesnar are two top 10 Mania matches of all time if not top 5, so that alone made WMXIX great.
4) WrestleMania XXIV - I would have ranked WM22 as #4 but Rey brought down that show for me. WMXXIV was pretty cool. I loved the MITB match and Mayweather vs. Show was a pretty cool concept. I thought HBK vs. Flair was not as good as everyone says. I was not a big fan of Edge vs. Taker either. The triple threat with Cena/Orton/HHH was at the same level at Taker vs. Edge. They were okay matches but I didn't think they were WM worthy.
5) WrestleMania 22 - This was a pretty random WM too. HBK vs. Vince and Edge vs. Foley made that PPV for sure. Both were great memorable matches. The tag team title match was odd, the Booker/Boogeyman was just stupid, and MITB has LASHLEY and RIC FLAIR. If that doesn't scream random I don't know what does. Mickie and Trish had the best Women's match I have ever seen, really zapped more life into women's wrestling since even back then it was lacking. If not for the crowd, Cena vs. Triple H would have sucked. Like I said Rey's victory brought it down, I did not like that at all.
6) WrestleMania XX - Loved the Cena/Show opener, it was a solid opener but unfortunately had a pretty lack luster show to follow. I still don't see the hype over the triple threat. Angle vs. Eddie was a great match, loved watching it, classic Eddie. If WWE didn't completely crap all over Lesnar vs. Goldberg this PPV would have ranked higher. Taker and Kane was well built up but the match was forgettable. I lol'd at the Rock's promo then Rock N' Sock vs. Evolution. That's all, that stuck out like a sore thumb compared to the rest of the card. I enjoyed that match though.
7) WrestleMania 23 - I struggled to distinguish which was worse, 25 or 23...I had to rank 23 higher because it had more than just one good match. HBK vs. Cena, Taker vs. Batista, Benoit vs. MVP, and the MITB were all enjoyable matches compared to WM25's ONE GOOD MATCH, it was a great match though. Kane's match sucked, the women's match sucked, Battle of the Billionaires bombed, and...wait...was that it?
8) WrestleMania 25 - It was watchable, but painful. I ordered it and it just went downhill right from the start. It didn't have the WM feel, except during the Taker/HBK match, that did not deserve to be on such a crappy PPV, but if not for that this WrestleMania might have not even existed.