Do you have a few miles in one program, added to which 25,000 would help you reach a threshold?

If not, put it where you'll get most use, one of your accounts with a larger balance. It really depends on your flying patterns, your home city, etc.

For me, I don't cash in awards for 25,000/domestic flights. I can buy those for $300-$600. Instead, I pool my miles and cash in at least international C, if not F.

I am flying to Germany this weekend for a week, on an award with LH in F. Today, I priced out the exact flights on which I am booked; if I were to buy the ticket, today's price is $18,563.00

So, your own usage probably dictates into which account you should deposit the points.