Hey!
I really really like the first cage!
This is because the first one is like a dual setup let's say. The cockatiels you get will be in a pair and with keeping two birds in the same cage, it can reduce space for each bird but also you never know if your birds are going to get along.
So with the first cage option, they can still be next to each other but there's a barrier in between (I think) to prevent mishaps occuring if the birds don't happen to be fond of each other. The dimensions also look great and plenty of space, which the other do have as well.