vicklemos: Oh yep, V is tough and rewarding. PCSX2 all the way!
But IX is by far the best one of this bunch. Memorable and surprisingly awesome ;)
DaCostaBR: Oh you filthy emulator user!
I played it on the NDS, didn't even know there was a PS2 version until now. I think I sort of prefer the sprites from the NDS than the polygonal look of the PS2. It's weird, it came out on the same year as DQ8 but I remember that one being better looking than this.
Never played 9. DQ4 or 6 were next on the list but I never got around to them. Now that the 3DS remakes are coming out I don't know if I should play DQ7 for the first time or buy and play 8 all over again.
PS: DQ8 had an optional dungeon after the credits that gave you access to the real ending, but my game always froze during the credits so I never got to play it :-(
Personally, I find that my least favorite entries in the series are 5 and 8. 5 suffers from a plot that is too heteronormative and doesn't treat female characters as well as its predecessor (it also was the first game in the series since the first 2 to lack the option to play as a female character), as well as the monster recruiting mechanic being annoying (I like using monsters, I just don't like it when getting a specific monster has a 1/64 chance per encounter that the monster appears in) and the fact that, for some reason, you only get 3 characters in your active party (that last problem was fixed in the remakes). 5 also was rather cutscene heavy (by DQ standards), and the game was generally too easy (except when the game decides to kill you with Sacrifice or Chance).
8 suffers from general slowness (unskippable load times don't help, nor do the extra animations), lack of party customization, a skill point system (with the flaws of said system), fewer strategically interesting combat options than 6 or 7 (where's the skill that lets you do extra damage at the cost of HP, or the one that makes the user take attacks meant for other characters?), and the same difficulty issues as 5 (game is too easy until an enemy decides to use the Dance of Death). There's also the fact that the characters aren't balanced; when the mage can do more physical damage than the brute character, you know there's something wrong. Also, why does the bank come so late in the game?
Anyway, my favorite games in the series are the remakes of 3 (the original has some horrible HP/MP growth mechanics that ruin the game for me) and the original of 6 (the remake removes monster recruitment and isn't as balanced, but it at least plays faster and has party talk, so it is still worth playing).
As a side note, I really do like the original version of the first game in the series; it's a very unique experience that does not feel like a typical JRPG. (I think I prefer it to the remake because said remake drastically increased the EXP and gold dropped by enemies, making the game *much* shorter.)