Your asking a pretty personal question. Depends on what you're going to do with it.
There are many great barrel makers. Lilja, Broughton, Brux, Kreiger, ... and on and on.
Length, contour, flutes depend on what you are willing to carry.
Twist depends on what bullets you want to shoot. Long heavy bullets need a faster twist than short light bullets.
I'd suggest reading many of the hunting posts on here. Pay particular attention to the ones that have a similar hunting style and conditions you are likely to encounter. See what type of rifles they are using. See if there is a trend that will help you decide what you need.
A custom rifle
costs a lot of money. It would be a shame to not get what you want/need.