You could compare them to Stereolab, in this regard. Another pioneer of post rock, and another one of the first bands to be given that label. Another band largely influenced by both Krautrock and jazz fusion.

Intriguingly, the two bands began at approximately the same time, on opposite sides of the Atlantic.Each came up with a sound that was drawn from similar influences, and would be grouped together as part of the fledgling post rock movement, quite coincidentally at the same time. I’ve always thought that was kind of cool.

[EDIT] I forgot to say what I voted for. Quite possibly because it was the first Tortoise I heard/bought, I’m going for TNT.

[Another EDIT] I don’t know about anyone else, but I’ve always found it strange that Tortoise are in PA, but not Stereolab. Not that I’m suggesting they need to be, or that I want them to be. Just saying… 🤗😉

Like both albums, very good band, saw them at Big Ears. Nice stuff.

One band I really want to see!!

Tortoise are very important to me, because when I heard them on the radio in the 1990s, probably just after "Millions Now Living..." came out, they were the first band I heard of to be referred to as post rock (even though I knew the last two Talk Talk albums at that point already). I loved what they were doing, so they were my gate to this new genre with much great music to come for me, and I love them to this day. They're one of the few bands that opened a new approach to me, very original and unique. 

Regarding the poll, I'm very fond of It's All Around You even though most don't seem to appreciate that one much. Then probably Millions Now Living Will Never Die and The Catastrophist. But I like all their albums and they have never let me down.

Amazing live band

Somewhat sad to see Standards without a vote. But I didn't vote for it myself. I suppose Millions Now Living Will Never Die and TNT have the most "classic album" feel to them (and it's well deserved). But I really like that although completely different - the playfulness of Tortoise is somewhat back on their fourth album. Not that it was ever gone. But I feel those two abums in between are more sonically unified (not a bad thing). Standards is more sprawling and full of different ideas. It's like their Gentle Giant-album, where each new track is its own universe.

As for those three later albums, they're alright but sure feel a lot less essential to me. Revisiting them I found It's All Around You less of a bore than when it was brand new. It's very nice. I suppose I wanted them to continue in a more wildly experimental direction, but instead we got a non-intrusive "couple over for dinner" slice of post rock. I much prefer that to whenever they attemnt to do "straightforward rock" anyway (something they do more often on the last two options in the poll). Seeing them live was a huge dissapointment to me as they killed all their wondrous beauty and magic with rocking out hard. I had a similar experience seeing Stereolab live as well.

I saw them on the tour for Catastrophist and they were celebrating their subtlety there rather than trying to rock hard. I liked this a lot. My weak spot for The Catastrophist and It's All Around You may well have been influenced by what they did there. I'd not disagree with you regarding which albums are more important and inventive. I voted for what I like to listen to most, and I am well aware that there are good reasons for preferring other albums when it comes to more (apparently;-) objective criteria. Standards is a great album, and I should probably have listed it among my favourites, but ultimately I like them all and there isn't much between all of them. One way I'd interpret the later albums is that they are in some sense a product of having found their sound. They are somewhat less adventurous for sure, more about furnishing the place where they decided to settle. There is a relaxedness and maturity about them that I like. I wouldn't complain for sure if they came out with something more experimental again though.