I agree that Third/Sister Lovers is awfully morose, but I think it has several good songs on it, such as "Thank You, Friends", "Stroke it, Noel", "Blue Moon", and "Nature Boy".
Damned right! Present Tense is, in my opinion, one of the very best power pop albums in existence, and "Now and Then", from that album, is one of the very best power pop songs. I also love Shoes's 1989 Stolen Wishes, even though it's a departure from their guitar-heavy signature into more synth-driven stylings, and can hardly even be regarded as power pop. "I'll Follow You" and "Inside of You" are among their best songs.
I like Twilley as well, though his ever-reverberating vocals can get on one's nerves. After a while, all his songs sound the same. I actually think his latter-day album, The Luck, is his best work. I know all of his old albums, but haven't heard anything since 47 Moons. My favourite song of his is "Perfect World" from the outtakes album, Between the Cracks.
As for The Raspbs, the best-known group of the three, I am somewhat ignorant. I have a compilation album of theirs, but I never delved further.

Other power pop albums I think are among the best I have heard include, The Searchers's 1979 self-titled album and 1981's Love's Melodies. Some of the most polished musicianship I've ever heard, even though most of the songs were written by others; Marshal Crenshaw's self-titled debut, with the superb "Cynical Girl", one of the most glittering and infectious songs ever recorded; Richard X. Heyman's brilliant opening trio of albums, though I think his best song is the astounding, propulsive "World of Indifference" (check it out on Spotify) from the album Heyman, Hoosier, and Herman.
Not albums, but a few of the outstanding power pop songs, I think, are The Plimsouls's "How Long Will it Take?", "Now", and "Magic Touch" (most people cite "Million Miles Away", but it doesn't do much for me); The Records's "Starry Eyes", a standard; overlooked band The Rubinoos's "Drivin' Music" and "Amnesia"; Bram Tchaikovsky's classic, "Girl of My Dreams".

Yes, but was the band critically slighted its entire career? I don't know that. That's where my "overrated" and your "ironic" don't jibe. I know it had no commercial success until decades after its dissolution.
OK, peace. Your previous reply came across as shrill and belligerent, which is why I used the phrase "shrieking adulation".
Just to be clear, we are all simply expressing opinions here. I say things people strongly disagree with, as does everyone. If people absolutely adore Big Star, why would that bother me? I respect that. I don't mind, just as I don't mind if someone thinks my favourite band or song is merely middling or crap. It's simply a difference of opinion.