Wouldn’t say Ardent is an alternative to a HR2, but would tick the XC boxes. I think of it as a High Roller Lite. It’s similar ramps but shallower knobblies. Less grip, more roll.
Ardent Race I’ve not tried and gets a lot of recommendations but sounds like it’s a dry weather tyre really. I’ve been using the regular Ardent on the rear of my hard tail to keep up with night ride guys, but also has grip enough for odd bits of steep and technical, loam and even mud. The Race version I think might be better for hardpack or dry.
HR2 is very grippy but is quite draggy on relatively smooth stuff. Old HR rolls more and is lighter, but not so grippy.
I like the HR2 rear combined with Minion up front*, but that’s my combo for more down than up or flat. Good in all kinds of conditions. I wouldn’t use the HR2 on my fast xc rides. I’d be struggling a lot with it.
* Minion up front always for me anyway.