i’m guessing when you say challenges you mean 30+ miles. XC is about 25-30 all in. Also, top 1/3rd out of 500 competitors only put you in top 160 or so.
What do all/mainly all top riders ride. Well frame choice is up to them, whatever is in there budget or supplied by shop/sponsor but generally will be carbon and HT. If your going FS then a spark/superfly 100mm is sufficient. Mostly HT though because nothings to technical to be needing anything more. Component choice will be mainly xt/xtr level with generally light wheelset (crest rims on 29er weight). finishing kit is personal but its mainly light carbon kit ( see kcnc/mt zoom etc), brakes are max 160mm rotors and forks max 120mm (mainly 100mm tho on 29er especially). Your bike therefore is personal choice but it should weigh no more than 23lb tops, head towards 20lb if possible. You cant go wrong really and there is no correct answer, try before you buy and upgrade where possible
Once you get your bike as you would like it, get the training in. Thats where the great are seperated from the good