Hmmm interesting topic! Three that come to mind for me are
Wildside with Under The Influence,
Cinderella with Night Songs, and
Shotgun Messiah self titled. The Wildside and Shotgun Messiah albums are both in my all time top 10, but Shotgun's 2nd & 3rd albums suck and Wildside pretty much disappeared, haven't even bothered with their other release. And Cinderella I don't like after Night Songs because they went too bluesy, I like about 4 songs on Long Cold Winter and hate the 2 albums after it, but I love Night Songs!
Alot of glam/hair bands from the late 80s & early 90s only released one album, or only had one notable or major album worth getting, and then either changed their style and went crap (90s/alternative) or only put out CDs of demos and live stuff or unreleased/dropped albums coming out 10 years later through Perris, etc. Here are some examples of bands who fit into this category, that I like just for that one album then either disappeared or only put out stuff I'm not interested in or independent demo/live/unreleased CDs.
Pretty Boy Floyd - Leather Boyz With Electric Toyz
Roxx Gang - Things You've Never Done Before
Tuff - What Comes Around Goes Around
Heaven's Edge - Heaven's Edge
Hericane Alice - Tear The House Down
Johnny Crash - Neighbourhood Threat
Arcade - Arcade
Trouble Tribe - Trouble Tribe
Gypsy Rose - Prey
Silent Rage - Don't Touch Me There (they had an rare earlier album Shattered Hearts but I dont like it)
Spread Eagle - Spread Eagle
Cats In Boots - Kicked & Klawed
Hurricane - Over The Edge
Heavy Bones - Heavy Bones
Candy Harlots - Five Wicked Ways
Roxus - Nightstreet
Etc.