Open ended question... I use a variety, depends on the need.
DeWalt 087k is a horizontal/vertical line level - self levelling, going on a decade without issues still checks out against my stabila 8' level every use.
Have a Hilti PMP, it basically is a 3axis plumb-bob. Self levels too. It's been in for service - some idiot tossed it in his tool bag after a long day not in its case... Spent the night next to my big magnet for cleanup. Didn't work so good after that
Have a bunch of dollar store laser pointers on 3d printed holders, so I can just slap them down and have a visual straight edge.