Oh boy, I think I might be heading for trouble here, but a lot of the bands mentioned in this thread are just plain awful. Rush, Journey, Styx - this is some of the worst "rock and roll" of my lifetime. I'm sure the keyboardists were talented technically, but the songs are such dreck it's hard to appreciate them.
Fagan was a great choice, so is Elton John. Roy Bittan of E Street is another great one. Try Garth Hudson from the Band, Steve Nieve from Elvis Costello and the Attractions, Stevie Winwood, and Leon Russell.

David Sancious' solo on Kitty's Back from Springsteens's "The Wild, The Innocent..." album.

Also some good piano on that album's, "NYC Serenade".

The wild, the innocent... Still is my favorite vinyl album to listen to with headphones on.

Calling Rush "plain awful" and some of the "worst" of your lifetime I don't believe is fair. Obviously, music taste varies between everyone and people always believe that what they like is the greatest. Debating music is kind of pointless, I guess. I'm not saying that you have to like Rush, but they are a good band. First off, they are a 3 man band which is pretty darn good for the quality of their work. Watching Geddy Lee do the vocals, keyboard, and bass is pretty impressive. Neil Peart is also a great drummer. I don't really think that is opinion, either. He has won numerous awards for his drumming. Also, this is from Wikipedia:

"As a group, Rush possesses 24 gold records and 14 platinum (3 multi-platinum) records.[4] Rush's sales statistics place them third behind The Beatles and The Rolling Stones for the most consecutive gold or platinum studio albums by a rock band."

^That's pretty darn good company for an "awful" band. I don't want to sound like some Rush "nut." I know a good number of their songs, not their entire discography, but they are not my favorite band. Just trying to give them some credit. (I'm NOT Canadian either, haha).

I know, I know, that's why I started with the disclaimer about heading for trouble. Of course it's a matter of taste, but I think they are awful regardless of their sales and popularity. I certainly don't think much of the movie Titanic, but it's the all-time box office hit.
Also, as I said, I'm sure they are technically proficient musicians, but the music is just so contrived and pretentious - of course, just my opinion. My tastes run much more to raw, passionate music. Rush, to me, is sterile showmanship.

I don't know how good he was technically, but Jerry Lee Lewis was a spectacular showman.

On edit: shouldn't really use past tense. He's still alive

And my avatar just reminded me of another piano player who came to prominence as a member of Squeeze and is a band leader and TV host in England, Jools Holland