A good NAS please

Hi,

I'm currently using a my book live 3To. I plan to buy a new NAS because I would like more space and to use Raid 1 option. I was thinking of a my book live DUO but I'm not sure that's the best option.

I would use it essentially for XBMC, music and a few backups. I would like to be able to connect it directly using USB and also to have access to it wirelessly. I'm looking for the best value for money since I can't spend to much money in it.

Any recommandation?

Cheers !