Stats...

[Evard]

In DnD there are the 6 str, con, dex, int, wis, cha

What about other systems?

I know in the Final Fantasy they use Accuracy and Vitality along with Mind and Luck (although what has luck ever been used for in the games?).

What are some other system's statistics and which are the best to use?

[The Rose Dragon]

In D&D, there are quite more than 6 stats. AC, BAB, saves, spells per day are all statistics, after all. D&D has 6 abilities, however.

Tri-Stat dX has Body, Mind, Soul. GURPS has Strength, Dexterity, Intelligence and Health. Qin: the Warring States has Metal, Water, Fire, Wood and Earth. Exalted has Strength, Dexterity, Stamina, Charisma, Manipulation, Appearance, Perception, Intelligence and Wits. Unisystem has Strength, Dexterity, Constitution, Intelligence, Perception and Willpower.

[Gralamin]

Tri-stat based systems use: Body, Mind, Soul

World of Darkness tends to have nine stats: Strength, Dexterity, Stamina, Intelligence, Wits, Resolve, Presence, Manipulation, Composure

Dragon Age (PnP RPG) uses: Communication, Constitution, Cunning, Dexterity, Magic, Perception, Strength and Willpower

The "Best" stats to use for designing your own system depends on what you want characters to be able to do, what sort of traits you want to customize, etc. It's not easy to choose.

[crazedloon]

I personally like the Dark Heresy set of stats

WS (weapon skill)
BS (ballistic skill)
S (strength)
T (toughness)
Ag (agility)
Int (intelligence)
Per (Perception)
WP (Will Power)
Fel (Fellowship)

due to the much clearer line between a few abilities most notable being the attacking characteristic. In DND if you are strong (or with a feat dexterous) you hit well but that is not always the case IRL so this allows you to be strong and still adept at close combat (the same applies to ranged and agility)
The other notable improvement is the distinction between WP and Per in DnD you can't be a sniveling little **** (wormtongue for example) who has no will power but is still very observant.

There are other reasons I like this better but that has to do with the system itself

[The Rose Dragon]

World of Darkness tends to have nine stats: Strength, Dexterity, Stamina, Intelligence, Wits, Resolve, Presence, Manipulation, Composure

Correction: New World of Darkness has those nine Attributes. Classic World of Darkness has the same Attributes as Exalted.