Guild Wars 2

In my opinion, it’s staff elementalist. Especially at level 80.

A level 80 staff elementalist has so many advantages such as :
Constant heavy aoe damage.
Permanent aoe swiftness.
1200 range on most of your weapon skills.
A good variety of combo fields (water, ice, fire and lightning).
Good support with might, fury, vulnerability, aoe blinds, conjures, condition cleanses and some minor heals.
Can chain up to 3 earth/ice elementals to tank for you for 3 minutes (before cooldowns apply). This makes soloing a lot of open world champions a breeze.

The disadvantages:
Low vitality and toughness. This is offset by dodges, CC, blinds, earth/ice elemental tanking and killing mobs before they can even touch you.

As for which race to pick, any will do. Although my personal preference is Asura for their animations, voice lines and tier 3 cultural armour.

for pure exploration warrior is the most convenient i would say

very easy access to movement skills (greatsword + sword/warhorn)
easy permanent swiftness (warhorn + Signet of Rage elite)

when full zerk you just cut through everything in open world

and you can skip and be faster at many spots by using sword leap skill!

Elementalist would be second choice
massive AOE dmg and still quite some movement skills (at least if you switch weapons when out of combat) + teleport skill