Damn all the album I have heard so far sounds a heck of a lot like Gratuitous Sax and Senseless Violins.
It almost makes a mockery of the claim that Pet Shop Boys ripped off Sparks claim. Noted that this was implied in the Sparks brother documentary. There have been quotes in some Sparks biography books that the Mael brothers are somewhat bitter regarding Pet Shop Boys success (as well as Queen success as well which I also think the connection is overstated). If you ever look at Sparks Fan facebook forums, this is treated as established fact. In fact when a Pet Shop Boy fan defended them from copycat status it cause somewhat controversy on the board.
I kind of get Sparks being annoyed at being a cult group while pioneering a genre of music that latter band would continue on and becoming incredibly popular with. Their circumstances is somewhat akin to an imaginary scenario where Led Zeppelin being a cult group that no one knows about while groups that followed their track Deep Purple, Black Sabbath became multimillionaires. However just like Deep Purple and Black Sabbath don't really sound like Led Zeppelin despite loosely being in the same genre. Pet Shop Boys doesn't sound that much like Sparks and found their own way and own voice within the genre that Sparks was one of the pioneers.
No. 1 In Heaven is really a transitional synth pop album of a "Rock 'N' Roll People In A Disco World". Despite the electronic instrumentation and synthesiser dominated music, it maintaining the rock and roll march like back beat/pulse mixed while incorporating some art rock elements. It has more connection in spirit to the likes of Chemical Brothers than Pet Shop Boys in a sense of rock and roll spirit but with electronic music.
Pet Shop Boys really is more of a dreamy lush pop version of synth driven music over a mid-tempo pulse (while in No. 1 in heaven it has a more frenetic energetic quality). At best only the first half of the title track "The Number One Song in Heaven" sounds somewhat like Pet Shop Boys.
However I actually think Sparks sound a hell of a lot like Pet Shop Boys. When Russell Mael starts speaking or sing/speak, his in their latter albums he sounds a hell of a lot like David Tennant. He particularly mimic the snarkiness/sarcastic tone. The whole spoken word verse, sung chorus of West End Girls over dream like music, Sparks emulated a lot. Hell even their chamber pop minimalism music when they abandoned synth pop of the 00's owe a debt to Pet shop boys in spirit in terms of the spoken word styling of david Tennant. The incorporations of strings (I suspect Lexicon Of Love Trevor Horn influence) into dance music is pretty similar to some of the strings/synth pop rearrangement of Sparks plagiarism album.
Gratuitous Sax is basically emulating Pet Shop Boys with the lush synth background with a mid-tempo beat. I also think melodically "So Hard" sounds melodically similar to "Let's go Surfing". THe keyboard riff in "It's a sin" sounds similar to the riff of "when I Kiss you" (also seems like Russel Mael likely adopted some of the vocal styling of David Tennant of the 'Itís a, itís a, itís a" in the later album)
Although I will say some of the "wham" synth strings sounds of So Hard and some of the somewhat reminiscent of Music that you can dance to and Pulling Rabbits out of the hat.
Thoughts so far that Pet Shop Boys albums I've heard so far seems to be more consistent from beginnign to end than Gratuitous Sax Senseless violins album (there is no Tsui Hark) although without the peaks (none I enjoy as much as My Way or See No Evil)