I've only played a few of them sorry.

DQ IX- Really loved how you could create your own characters and even choose what clothes to collect and wear.

DQ V- It's really cute how you start out as a kid and then grow up and even choose whom you get to marry later on.

DQ VIII- Can't remember much of this one sorry, but it was fun judging from some vague memories.

DG VI- I like this one the least. It just feels so... tedious so far. But I might pick it up and try and advance on, but at the moment it's really tedious.

What's IV like ? Is it good ? It's ranked so high on everybody's lists !