Personally, I played DragonQuest 2, Cobi Quest which was the first game to get me hooked on the series and also Monster Quest Caravan Hearts which was fun too but got repetitve. I would like to try out the other series too but I'm not sure which one to go for.
Honestly? My favorite is the very first game. I absolutely loved it and played so much of it on the NES.
The first and second ones, for me. I still remember the first time I moved from slimes to mandrakes, before I could pick up that copper sword. It never got old. I tried to get my kids to play it on an emulator, but as soon as they found out you don't respawn, they lost interest. :\
The nostalgic in me wants to say Dragon Quest 2. But the realist in me is undecided between Dragon Quest 7 and Dragon Quest 8. What Square Enix needs to do is make a Dragon Quest collection of the main series.
I have only played Dragon Quest IX, so I can honestly really say that that one is my favourite. However, it has definitely gotten me hooked for subsequent releases, and I now really want to go back and see what I have missed from the other ones.
Now this takes me back! My favourite, I guess, would have to be Dragon Warrior Advanced, one of the very first game I ever played. I really enjoyed the story and the variety of monsters. Second would be Dragon Quest VII, it was just a completely different experience; from the music to new monsters, the game-play and so on. Simply amazing!
Same, I still play it every now and then and I enjoy the fact that I can play for as long as I want after I beat the game, similar to the Elder Scrolls games.
Having played only V, VIII and IX of the Dragon Quest games, I gotta give it to V. The story was just nothing short of amazing.
The best is the first US NES version. The second title also for NES is a close second best. The rest are pretty much crap.
I agree with this, the first one was the best of the series in my opinion. I actually got a copy of Dragon Warrior on the NES for free when I subscribed to Nintendo Power. After a month of waiting, checking the mailbox every day for my new game, we decided to call Nintendo Power to see what was up with the delay. The next week, we go to the mailbox and there are TWO packages with a copy of Dragon Warrior in each. I ended up trading the duplicate copy for Teenage Mutant Ninja Turtles II: The Arcade Game which was what the first Teenage Mutant Ninja Turtle game should have been like, instead of the gruelling torture of the first one.
My very first (and favorite) Dragon Quest was VIII. I instantly fell in love with Yangus' character and story. The only other physical games I've played of the series were the two Monster/Joker games for the DS. I enjoyed them for what they were, but I think I liked the first one better.
Dragon Warrior was the first RPG I ever played, so I'm tempted to say that, but I have to defer to Dragon Quest IV. I love how it's split up into character-centric chapters, and I enjoyed pretty much every segment of the game. (Particularly Torneko's. You don't get to wander about as a merchant too often.) The DS adaptation is particularly good since you can better control your party.
In order of descending love: I, VI, VII. But, I think the first one was the one that really stuck with me thus far.
My personal favorite is IX, it's super polished and easy to get into for people new the series. The older games are all pretty great as well.