I thought the “here” was Northern Barrens ?
But you can’t really go wrong if you’re doing quests that aren’t grayed out in your questlog.
After finishing up in a starting zone (which is usually Mulgore for Taurens, Durotar for Orcs, Eversong for Blood elves, …), I consider (Northern) Barrens to be one of the more solid options to spend a couple levels, but we’ve all got our own differing tastes.
I could say it’s mostly because the zone received a freshening up during the Cataclysm expansion (which is more recent than for most other lower level zones), a few cosmetic improvements, the quests having access to some more modern features, but really it’s just because you get to kill harpies, you get to kill lots of them, and nothing beats that, other than killing even more of them.
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Assuming you didn’t hang around in Durotar too long, you’ve now left the world of starting zones, and you have a lot more options on where to spend your time.
If you feel like a change of scenery, have a look at the big map and see which zones have level ranges that include your character level. I’m (wildly) guessing you’re somewhere around level 20 to 25ish at the moment ?
If that’s true then you have about a handful of zones nearby that you could level in.
At level 20 you also unlocks mounts, which is great, that will allow you to get around faster, i’m sure you’ll be directed to look into that when you ding 20, but if not just fly your way back to Blood Hoof village in Mulgore and find a Kodo that fits.
With the increased mobility that brings with it, you could potentially even consider playing in some of the Zones on the other continent (in Eastern Kingdoms), as opposed to Kalimdor which is where you’ve spend your time so far. Kalimdor has a bit more options but the whole Hillsbrad/Wetlands/Arathi area in E.K. has its appeal too.
To get to the other continent, you could either take the portal/zeppelin to the Undercity in Eastern Kingdoms (from the big tower next to the flight master in Orgrimmar) this puts you in the Northern part of Eastern Kingdoms.
Or you could go to the town of Ratchet in Barrens where there is a ship that can take you to the jungles of Strangletorn (the southern tip of E.K.).
Or you could stay in Kalimdor ! Go whereever the Kodo leads you. Aslong as you don’t end up doing grey quests, and you see quests around, there is no bad place to level.
Andddd of course you now also have the ability to queue up for Dungeons to meet some other people and kill stuff together.