Hey, OP. I'm new to Windows Phone, bought a Lumia 1320 to replace my Note II. It was the only option for me given that my carrier doesn't have the 1520 or 1020 in stock. After using WP for a few weeks, I've come to like it and want a "better" one. I too was looking at the 930 and 830 and between those two, I'd go for the 830. Mainly for the interchangeable backs and thinner profile. There's a good comparison video on YouTube by phonedog if you want to get a better idea of how they stack up.
The only reason I haven't gotten it yet is because I'm trying to find a good deal on a 1520 since I love the 6" screen!