For choosing a base class you can ignore most stats. Faith, int, vit, end, res... all pretty useless. Att is only for pyro (why even play the challenge?), str and dex are for weapon variety.
You're going to be two handing, so 11 str is enough for almost anything you could possibly want (14 str gives you like 3 new options, none of which are great) and dex is way more important. Hunter is best for weapon variety, while warrior still keeps it interesting. Weapon selection on everything else is pretty bad... and anything with less than 10 dex is abysmal. Do keep in mind Hunter and Warrior have no attunement slots, which is probably for the best in a challenge honestly. If you want to spam combustion spells sorcerer is best.
dozingdevil posted...I don't get everyones fascination with a SL1 run. it's not the hardest base level run.
Lots of people go no-pyro SL1s and you simply can't pyro your way through 4K past NG++ (I'd be very surprised at least). If we ignore the two att and assuming you're playing without pyro then it's one of the most painful classes to use in the game only rivalled by Cleric and to a lesser degree Bandit. Painful in this case doesn't necessarily translate to difficulty, just boredom.