This might be the most complete and solid Dragon Quest experience I've played. It has fun, well balanced characters, a well written and sympathic antagonist, and a chapter system that's basically a long and engaging tutorial that slowly introduces and ramps up all the different gameplay mechanics. By the point where the game truly begins the player will already have a full understanding of the battle system, and familiarity with all the characters and their backstories. It's very smartly designed, for an RPG released in 1990.

The one downside to the chapter system is that every chapter starts with new characters at level 1, so you won't get very far without spending some time grinding levels at the start of every chapter. Besides that I think the overall progression of the game is well paced, at about 30 hours. More RPG's could do with not being so absurdly long.

I think Dragon Quest IV is a good RPG for beginner players to pickup and enjoy since it's not a very hard game, and also as a starting point in the series. I'd recommend either the mobile version that has the party chat feature, or the DS version with the party chat modded back in. Party chat adds so much personality to this game and its characters that I couldn't imagine playing it without it.