Well, Scott, do you like your ladies tall or shorter? A lot of it is just personal opinion. Then there is always the thought of going for a 39" barrel, get right in between.
Benefits of a longer barrel: 1) longer sight radius should improve accuracy a bit; 2) Gives the powder a longer time to burn, so your muzzle velocity would be a bit faster.
Disadvantages: 1) If you are planning on hunting with it in brushy country, it is a little more awkward to get around in; 2)It weighs a bit more so there is a bit more fatigue factor there; 3)There are bound to be more ideas both ways, just cannot think of them now.
And then, the style of the rifle dictates barrel length as well. For example, an English Sporting rifle really would not look right with a longer barrel. I always liked 32" barrels on mine. And on the other end is the thought of a nice southern mountain rifle would not look right with a 24" barrel.
IIRC, my Leman had either a 36" or a 39" barrel and it balanced very nicely.
John (Bigsmoke)