Depends on what you are doing, longer wheelbase is more stable, but harder to get the front wheel up.
Slamming the rear wheel increases stiffness of the back end, and stops rear wheel slipping forward without tensioners.
The main reason for slotted dropouts is for tensioning and allows for sprocket changes without altering the chain.
I'D say the middle of the drops with a 44t allowing 1 tooth either way without splitting the chain.