Dragon Quest IV DS is the best one. However, it has a horrible localization with missing party chat, tons of changed names, hard to read accents and etc. Pretty much, its a fun game that's missing its soul.
Dragon Quest Monsters Joker is excellent and the translation wasn't tampered with much. The gameplay and everything is 100% left in tact. I would definitely recommend this.
Dragon Quest Rocker Slime I have yet to play, but I hear its good.
Dragon Quest V is coming out in 4 days. It is suppose to be better than IV with the localization, with party chat put back in and no edited scenes or anything. Though still some accents for some characters and pretty much every name was changed.... So we'll see how bad it gets.
Six upcoming games you should look into:
