Amex Plat
I've been using Delta, easy process, buy 4 x $50 all at once, reimbursed right away, certificates emailed right away.
Switched to Alaska this year.
My experience:
Don't try to buy these while you are logged into your Alaska account, it errors out every time.
The first one I bought at $50 I selected the email option. Never received the email with the PIN code. Called customer care and they were to email me a copy. Never received it. Called again and did get the PIN emailed. Customer care agents have been very good to deal with.
Second and third $50 was purchased using the print feature. Was able to print with a PIN code on the certificate right away. This option worked the best for me.
Credit has been hitting my account 3 days after purchase.