Re: What is important for you when buying things online with bitcoin?
Most will give a window of something like 15-30 minutes for the transaction to be made, and after that the transaction will be cancelled to protect from price changes. However, there was one I used in the past which wanted the transaction to be confirmed, not just broadcast, within the 15 minute window. Even with a high fee, sometimes that is impossible if there is a longer delay to the next block being found. It was then a total hassle to get them to credit my transaction against a future purchase.
What a bizarre way to process invoices -- it boils down to chance. I've seen the network go 2 hours before without a single block being found.
I've had trouble with processors who have really poor node or API uptime/connectivity, and don't detect payments in time. CoinPayments invoices tend to time out no matter when you send the payment. I've also had trouble with CoinGate, although the experience seemed to improved the last couple times I used them.
Bitrefill's checkout process is very smooth. Other merchants and processors should take note.