I would recommend leveling as many teams as you can stand.
Most likely via boosting, once you have a capable booster.

If the Mages are your first toons, possibly quest or play them (at least the booster) to 83rd, 84th or 85th... so they can comfortably solo level 80 dungeons.

You won't regret having additional options at 80th, when RAF expires.
Plus the more toons you level, the more levels you can grant, which is even more toons.
Just be sure to use all the granted levels before RAF ends, they cannot be used after the RAF time expires.
You can eventually have a tradeskill empire, or not need to level from scratch... whatever the next boxing itch becomes.