1 A Night at the Opera - Queen, Blind Guardian
The best songs by these bands (or some of their best songs) are on these 2 albums:
Queen - Bohemian Rhapsody (1975)
Blind Guardian - And Then There Was Silence (2002)
(Blind Guardian titled their album as a homage to Queen because Blind Guardian singer was inspired by Freddie's multi-layered vocals).
2 Wish You Were Here - Pink Floyd, Badfinger
3 Brave New World - Iron Maiden, Styx, The Steve Miller Band
4 Up - REM, Shania Twain, Peter Gabriel, Right Said Fred
5 Merry Christmas - Mariah Carey, Brenda Lee, Bing Crosby, The Supremes, George Wright, The Brothers Four, Edmund Francis, Jackie Gleason, Bob Kames, Raymond Lefevre, Vincent Lopez, Johnny Mathis, Jim Nabors, Sir Malcolm Sargent, Andy Williams
I listed only 15 artists because the item title was too long and wasn't accepted but there are more:
Patti LaBelle and the Blue-Belles, Johnny Cole and the Robert Evans Chorus, The Vienna Boys Choir, The Mills Brothers
And I didn't even include albums titled "A Merry Christmas" but there are many with an "A", too.
6 Dystopia - Iced Earth, Megadeth
Iced Earth (2011), Megadeth (2016)
7 Secrets - Toni Braxton, Human League, Robert Palmer, Herbie Hancock, Gil Scott-Heron, Con Funk Shon
8 Shine - Joni Mitchell, Trey Anastasio, Martina McBride, Daniel Lanois, Mother Love Bone, Estelle, J.D. Allen Trio, Edenbridge, Rachel Fuller, Newsboys
Left off Bond (English Quartet)
9 Down to Earth - Rainbow, Ozzy Osbourne, Stevie Wonder, Chubby Checker & Dee Dee Sharp
10 Killers - Iron Maiden, KISS
The Contenders
11 Low - David Bowie, Testament
12 Awake - Godsmack, Skillet, Dream Theater
13 High Road - Kesha, High Road, Night Ranger, Midnight Shine, the Grapes of Wrath, Mark Bradford, the Present Moment, Byu Synthesis & Ray Smith, Elowvate, Dusk + Blackdown
14 Revival - Selena Gomez, Eminem
Maybe others as well.
15 Red - Taylor Swift, King Crimson
16 Still Life - Van Der Graaf Generator, Opeth
Van der Graaf Generator - Still Life (1976)
Opeth - Still Life (1999)
17 Dead Again - Mercyful Fate, Type O Negative
18 Guitar Man - Bread, Elvis Presley
19 Falling in Love Again - David Gates, David Sigerson
20 Superhero - Brian McKnight, the Laurie Berkner Band
21 Doom - Mood, Job for a Cowboy