The X Factor is an absolutely amazing release, and my 3rd favorite Iron Maiden album overall. There aren't many songs that are memorable after the very first listen, but there are plenty of great riffs, epic solos, fantastic lyrics, and an amazing vocal performance by Blaze Bayley. I really think Blaze sounds awesome on this album, his dark and subtle voice fits perfectly, and I seriously doubt even the best singer in the world (Bruce Dickinson) could match that. I actually think this is one of the most important albums in their career - if you listen to A Matter of life and death, you can still feel the elements from The X Factor present. It's just a fabulous record that I'll never get tired of. And, by the way, it contains my all time favorite song - Sign of the cross.
Virtual XI is a pretty damn good album as well, although easily one of my lesser favorites. Blaze doesn't sound quite as good, which maybe has to do with some of the tunes sounding more cheesy and happy. It's still more accessible than The X Factor, due to some catchier tunes. My favorites here are The Clansman, Como estais amigos, Futureal and The Educated fool. Even The Angel and the gambler is a fun ditty, although I agree the chorus didn't need to be repeated 20 times. It's an enjoyable album overall, and there's nothing about it that should make Iron Maiden ashamed.
When it comes to the live performances from Blaze era, that's where the problem is. We've all heard how do The Trooper, Hallowed be thy name and some more songs sound with Blaze on vocals. All I have to say is: Maiden should have changed the tuning to fit Bayley's voice better. That would give a new special spark to some of their older songs, and I would have been the first to accept the change. It's weird that Steve and the guys didn't realize at the time that Blaze wouldn't be the right guy for Bruce's stuff.
It's not that Blaze is a bad singer - if you check out his solo albums, you'll be blown away. I think he's got the most consistent band in the last 10 years in terms of quality of studio albums. I've seen him live a couple of years ago, doing an incredible acoustic show. Believe me, a bad singer can't sound so incredible with only one guitar beside him. It was impressive. He even stayed for two straight hours after the gig and signed everybody's ticket. What a guy.