Bontrager XR2 2.2. I ride a hardtail so like a little bigger width.

My findings:

Wider at lower pressures is generally faster. I experimented with a bunch of Vitoria Mezcal tires in different widths. 29x2.6 up front and 29x2.35 our back was noticeably faster than 29x2.1 both front and rear on my F-Si

Run something with more grip on the front. I ended up swapping out the Mezcal for a Bontrager XR3 up front. This is condition dependent. If I was on buff single track I would run Mezcals all day as it’s a very fast tire that behaves predictably when cornering. However down here in the southeast a lot of singletrack can have rooty sections and the Mezcal does not perform well over roots. XR3 is a great tire for roots. XR4 is even better but too draggy on anything long and smooth (I can actually feel it and I’m reticent to ever say that about any tire).

Schwalbe Rocket Ron 2.25 front and back.
Don't buy the cheap ones get the EVO