I have an upcoming round trip on Delta (STL-ATL-SAV) and need some advice from you wise old owls.

Do I put the miles in my UA or DL account and why? I have a reasonable # of miles in both accounts and am Premier, soon to be PremEx in UA; regular member in DL and unlikely to ever reach elite there.

As far as I can see, the flights are all on Delta proper (thereby avoiding the problem that UA does not give credit for Delta connection). All 4 flights are under 500 miles. I am unaware of any special promotions that may help me.

Does it matter?

Thanks in advance.

Lurker