From my experience anything physical related (Death Knight, Warlord, etc.) works well from the getgo as it doesn’t rely on items that much.
Also always had a blast leveling with transmuted Primal Strike (Vindicator, Warder) as it provides VERY good damage from early on while still being reasonably sturdy.
Vitality casters (Conjurer, Ritualist) are also insane atm. Very good defenses and still sick AoE.
My first build was a pet build which also crushed early. Just keep in mind that pet builds (Conjurer, Cabalist) are very different in style compared to other builds and you might get a completely different experience than with casters/melees. But they wreck stuff nevertheless.