I agree, both a within Visran's budget.
But since camera is a priority, plus since he is moving from andriod to WP8, i would suggest for L820, bcoz of 1GB ram, 8.7MP primary cam,1.5GHz processor, video rec of 1080p@30fps, and a removable battery.
Visran, you can check the link as well for a head on comparison.
Nokia Lumia 720 vs. Nokia Lumia 820 - GSMArena.com