I've had both, the Hyperion series, and The Expanse series sitting on my shelf for years now, and only ever read a little bit of the first books of both series.
I'm currently re-reading the Lord of The Rings trilogy, but after, I'm planning on reading The Expanse or Hyperion series.
Which should I read first?
Edit: Thank you all so much for your feedback!!
The general consensus seems to lean towards reading The Expanse first, so I think I'll read through Leviathan Wakes and then read Hyperion unless Leviathan Wakes provokes me to directly continue into the second book.
My opinion: Hyperion is a beautiful work of art. I was in awe reading it. You get your mind bent in different ways and it was glorious.
The Expanse is very good craftmanship. The authors took a lot of what is good about space opera and put it in this series and it is fun to read.
You should read both, but Hyperion first. (it also goes better with the epic experience of Lotr)