Trek Checkpoint AL3 or Giant Revolt 2 2021?
 

Which is the better gravel bike to get? Checkpoint has straight Sora while Giant is a mix. Checkpoint is tubeless ready but only has a max tire clearance of 38mm compared to Revolt which is 45mm. Price range is almost the same.

And what is the correct size on these bikes for a 5’7” height? These two are the choices my brother is looking at. He owned a Giant Fathom size medium. For the Revolt, he is in between small and medium on the Giant size chart.

Revolt all the way. Sorry don't think I can help on size. But fwiw I'm between 5'8" and 9" with 30" book measured barefoot inseam
I also bought the rlt9 rdo over the revolt. Went with a 53. I'd have bought medium revolt. My trance 29er is a medium, but when I test rode the fathom I liked the small.

Oh and I think the carbon Revolt is more comfortable than the RLT9. But I gave up my himod supersix for gravel. So leaned that direction on gravel bike purchase.

38mm max is narrow for a gravel bike. He'll want a Small if he goes with the Revolt.