I wrote a really long praise of Foundation before I realised that you've just said you already like it.. instead I'll just say have you read Caves of Steel and its sequels? They are set about 20k years before Foundation and are also very good

I'm not sure if The Expanse (TV series) ruined Foundation (TV) for me, if it's just not a good adaptation, or if the books are just not particularly adaptable (or all three), but I agree. I only made it through the first two episodes before I gave up. I've heard the second season is better, but I don't know if it's worth it to force myself to sit through season 1 for.

The Expanse is just spectacular when it comes to realising its world but also, with how much depth there is to the characters and politics, Foundation immediately felt very shallow in comparison. Obviously The Expanse books lay a lot of the foundations for the TV series to build on, but I think the TV series did a great job of adapting it to a new medium without much being lost in translation, and it even added to it in its own ways. Foundation's world-building, characterisation and politics all kind of just felt like it was going through the motions and showing surface-level stuff because it felt it had to rather than because it actually had any substance to work with. Which wasn't helped by the fact that the books don't provide much in that regard to work with.

Ultimately, I don't think the Foundation books aren't particularly well-suited to being adapted to the screen. It's so focused on the "bigger picture" - on civilisations rather than characters, on philosophical and sociological concepts rather than particular plot points, on macro-narrative - while TV needs characters and micro-narrative.

I will say that the TV series' idea to use three different-aged clones of Emperor Cleon, and to keep the actors persistent through the ages, seemed like a great addition. It's good to try to keep some recognisable faces while jumping across such long time periods.