DS 2 better!
I think ds2 is alot better because of things like the graphics are totally amped compared to ds1. Storage vaults, and also you can have team members in the inn, then you store items in them if you run out of storage vault space and dispand them and they will still have the items on them when you get them back!!! Pets are also available in ds2 instead of just pack mules, you can get things like , light niads, dark niads, ice elementals, scorpians,dire wolfs, lap dragons, and more!!
Ds1's multiplayer can have more players but ds2's you can get your other party members in multi-player also. Although ds1's multi-player is more free, ds2's have better monsters, including bosses which are stronger then their normal counterparts.