Skyclad's Folkemon is a good example of an extremely front-heavy album. It starts with The Great Brain Robbery, which is solid, if unremarkable. Then Think Back And Lie of England and Polkageist, two of my favorite Skyclad songs. And then...the rest of the album isn't bad at all, but nothing really stands out until the closing duo, Any Old Irony? and the cover of Swords Of A Thousand Men. Skyclad are generally like that...they'll have a few amazing songs, a few solid songs, and some that are decidedly filler.
In terms of albums that only have one good song, The Faceless's first album, Akeldama, has this song Pestilence that imo is pretty damn good tech death...pretty badass, fairly technical, and reasonably varied without devolving into a disjointed riff soup. Unfortunately, the rest of the album is pretty much shit.
Luca Turilli's Prophet of the Last Eclipse...Demonheart is fucking awesome, and the two instrumentals are really cool, but the rest is kinda bleh. Not bad, again, just...eh. Same for the first album, which has maybe two, three stand-outs (Ancient Forest of Elves, Legend of Steel) and the rest is just discarded Rhapsody material.
Also...don't hate me, but...Ace of Spades. I mean, you have the title track, you have We Are The Road Crew, and you have...what, exactly? A bunch of solid songs (Dance, Fast And Loose, The Chase Is Better Than The Catch, The Hammer, etc), but not remarkable. Overall a reasonably consistent album, and fun to spin, but definitely got a bunch of thriller on there.