So this is what you've got before LS.
1. On the Sunday of Life
EP. Voyage 34
2. Up the Downstair
3. The Sky Moves Sideways
4. Signify
5. Stupid Dream
To be honest, I think all of PT's albums before Stupid Dream tend to meander about. That's not to say they don't have good songs, they just don't have solid albums. I think Up the Downstair has the best collection of music out of these choices (their first album proper, as On the Sunday of Life is more a collection of tunes made up to that point with no real direction). Voyage 34 is a real test of patience. The Sky Moves Sideways has it's moments, but again, overstays its welcome. Signify is a nice listening experience, and would be my second recommendation, but it tends to have a lot of atmospheric filler. For example, a song, then a track of ambient noise, another song, more noise, etc. While Stupid Dream represents their first conventional album, even I'm not big on that.
I know there are fans who love these albums, but for me, they're interesting pieces of work before PT really pulled their shit together.