Specialized Epic, Scott Spark, Trek Superfly or Top Fuel, Canyon (nerve?, it’s very old school whatever it was). I suspect of that list the Anthem 29er is most likely to be the more budget friendly and abundant secondhand.
FWIW I borrowed an ‘early’ 29er FS a few weeks ago and was surprised how weird it felt. Yes the handling is sharp up front, but the long chain stays make it feel a bit weird changing direction at speed. Longer and slacker front ends really help on 29ers to make them feel balanced (in the same way 650b bikes have grown longer chain stays as front ends have got slacker to the point where most bikes now share similar geometry regardless of wheel size).
I’d be tempted by something a bit newer, but that depends on the type of rider he is. Some people are a bit “princess and the pea” about such things, some people need all the help they can get to not go OTB as soon as they glance at an old school 110mm stem and 71deg HA, and some people are fast pretty much regardless of what bike they’re on. So kinda depends on budget and whether they would notice that a modern XC bike is a good 3deg slacker and couple of inches longer than 10 years ago.
