Each skill cap depends on how you spent your base abilities and skills you are leveling. For example my character with high agility had 331 stealth (without cloaking device) and char without high agility will never have such high stealth level.
~120 for hacking and lockpicking. With haxkey you will have 135 points, more than enough to open all closed containers and doors in the game and to hack all the computers
~90 for traps, maybe less
~160-165 for crafting skills if you're lucky enough to get high quality components and maybe even more for perfect infused ancient rathound leather, up to ~200 tailoring.
For stealth - the higher - the better if you are usung snipe and ~ 215-250 for critical chance 100% if you're using ambush. Still the more the better if you want to remain in stealth mode right in front of faceless gaunt or crawler.