Much depends on your situation - ranges, size of deer, etc.
As Dphar will acknowledge when in the West, ranges can run to 200yards, rarely closer than 50 yards, unless using a tree stand, in a grove or copse of bush. Thus, lowest trajectory coupled with longer range accuracy is a must.
A .54 or .58 would be a good choice. Larger powder charges and tighter combinations must both be used to achieve this.
I might start around 3 drams (82gr.), but likely would start at 100 2F and go from there. I suspect something around 120 might serve the best in both accuracy and lowness of trajectory, giving a point blank range of about 135yards, thus a 150 to 200yard shot could be made with little effort, although such practice is necessary.
I sold my .58 SXS as it would not regulate with more than 110gr. of 2F - not enough imho for moose out to 200yards. The .69 still has that job - if, a ML is used.
Maybe Taylor and I will have a 14 bore hunt this fall?