I’ve been in this position before and chosen the carbon hardtail. Weight was a big factor in that decision, since an aluminum frame with more complexity, not to mention a shock and bearings, links, etc will end up weighing quite a bit more than a comparably priced carbon hardtail frame.
Component wise, at the Comp level you’ll end up with the pretty much the same parts on each bike. This choice comes down to whether your local trails are on the rougher side or you value comfort over speed. A hardtail in skilled hands can be just as fast, but it’ll be a bit of a rougher ride. Either pick will end up being a sweet bike for XC racing though!