As an owner of both a Librem 5 and a Pixel 6a running GrapheneOS I can confirm that the latter has been much more reliable and has taken substantially less work to get to the point where I can daily drive it. The Librem 5 is not there yet, and while I would like it if it were I'm not currently very optimistic about that.
In the past year, I have used a pinephone+keyboard with Arch, a oneplus 6t with postmarketOS, and a pixel 7a with GrapheneOS. In my opinion, Graphene is significantly easier to daily drive because the applications are designed for a phone's form factor.
The biggest one is the Firefox ESR build from the pmOS repos with the custom userChrome.css that tries to fit everything onto the Pinephone's screen. I pretty consistently encountered pop-up prompts (for example, in the built-in password manager) that ran off the edge of the screen in both portrait and landscape. Zooming out sometimes helped, but then the text was unreadable and the buttons too small to press. There was also no forward button in either the overflow menu or the nav bar. The Phosh settings app had similar problems.
There's some hiccups when you first set GrapheneOS up, but after that it is as smooth as, and blends in with, any other Android device. I've never used Librem or PinePhone to comment on them
