My first experience with PT was 'Up the Down Stair' from about 1992, which was also about when I encountered it. Then 'Voyage 34', 'Staircase Infinities' and then the 'new' album, 'Sky Moves Sideways'.
These albums were right up my alley- a lot in common with the happier, trippier Floyd pre-Dark Side, with some strong Kraut-rock influences, yet still its own aesthetic. I like them so much that I forgive anything that has followed (most of which I enjoy a lot). 'Signify' brought a new sound for the band, less of the amazing jamouts and more harmonized vocals (usually with dark lyrics). Later albums confirmed that pathway, more song/pop oriented, but the roots are plainly obvious to me with any of their work to date.