I know the only thing I can say about cage size is that my old quaker was fine in a small cage, as soon as I put him in a larger cage he got really cage aggressive. He was the sweetest bird for 3 years in the smaller cage, as soon as he got his huge cage he got really mean, so I put him back in old cage and the sweetest bird again. So it all really depends on the bird I think.
I would check make sure you have enough toys and perches that he/she can move around easily.
I have decided to go with this cage Bird Cages & Aviaries: Prevue Wrought Iron Flight Cage F040 w/ Stand instead because I realized a couple weeks ago that I don't have a space for that other cage. But I think Riley will be plenty happy with this one. I will be ordering it friday or saturday. And should hopefully get Riley on the 7th.