where to drill?

[outtafocus]

I will be drilling my tank within the next week and a bit. I have two choices of where to drill the hole for my overflow exit.
My tank is made of 1/4" glass all around with a 1/2" bottom.
Question is, should I drill the 1/2" straight out of the bottom of the tank, or drill the 1/4" back panel and 90degree out of tank to flex tubing?

Drilling the 1/4" will be alot easier, but will exiting out of the back of the back reduce my flow?
I will be using 1" pvc so the hole for my bulkhead will be 1 3/4".
What do you think?