I would say 4 is my favourite, but obviously I have a fairly large bias towards it considering the number of times I played it and that it was one of the first really great RPGs I ever played; it was between this and Phantasy Star 2.

The one thing 3 had over 4 (from my childhood memories) was that 3 had way more monster arena stuff that I liked. That was a major thing back in the day.

Although after finishing 5, I can say that 5 is my favourite now. 8 is also very good, but too spread out in a similar way to FF12 (though not nearly as bad). Dragon Quest 5 is now among my favourite RPGs of all time; it is a very powerful game. I LOVE how there is so much optional commentary from the different characters after almost every room, event, and person spoken to; it gives the game tremendous depth, and it is implemented very well (it wasn't in DQ8).

The only 3D RPG I have played that has really done the whole large world thing correctly is Skies of Arcadia (in my opinion). Xenosaga and FF10 are good, but they don't follow the SoA/FF12/DQ8 style of play.

3 n 5 are very popular in japan, but i like 4

To me it's DQV without a doubt :)

It's also one of the best overall stories i've ever seen in a video game, plus the whole generational leap is very well done.

I've played them all with the exception of VI, and my favourites are V and VII. V has my favourite story in the entire series, and VII has the most rewarding gameplay/job system.

why DQ series didnt huge succes like FF in overseas?

ppl needs better graphics n good looking hero ?

III, V and VIII. However, never played more than III, IV, V and VIII. (IV is also nice, but i didn't like the way the story was splited)

I also only played DQVIII and it was more than awesome.

played III, IV, V, VIII and completed IV and V. DQV is one of the best RPG games, not the best. IV was fresh since it introduced the chapters(stories) for each supporting parties before everyone meets in Chapter 5.

Marketing is the reason, in my opinion. I don't think graphics are the major deal, look how popular Wii and DS are this generation, with weaker graphical technology. It's not like the DQ games are ugly or anything, they have some very good art in them. I do think it has the appeal that it could be a very popular series outside of Japan. It just needs to have the proper channels for getting the word of the game into people's ears, and the game itself into player's hands.

Anyway, the irony is that the game was made with a western market in mind. Considering the game was medieval fantasy, it wasn't expected by anyone to do very well in Japan. The first one was a surprise hit, and the series has never had a weak moment, and has trended upwards in popularity since it was introduced.