One thing worth consideration.
Take a look at some of the "twink" brackets.

There are quite a few in the 70 Twink and 80 Twink categories.
Those brackets are: 70-74 and 80-84.

If you want to be able to arena, you need to stop at 70th or 80th respectively.
If you don't care about that, being higher is better stealth detection or stronger stealth.
It is more health, and stronger spells/abilities.
It is slightly less dodge (or whatever), for the same dodge rating.
Not sure how that compares with stronger spells.
If you're a Paladin, 72nd for Avenging Wrath is probably worth not being 70th in the 70-74 bracket, unless you want to arena with your team.
Turn off experience once you reach your desired level.

A major benefit is the gearing.
It is around 2k total honor for a full set of level 70 PvP gear.
Once you gear the team up, you have the best gear for PvP in every slot.
And you'll never need to re-gear the team, unless you want to level up again.
Everyone else has the struggle/fun of trying to get the new season armors; a new season doesn't change the best armor you could wear at 70th in pvp.

Depending how you look at it, that is a mixed blessing.
You're only playing pvp because it is fun, not because you want to upgrade the gear.
It is a relatively level playing field.
No one will ever beat you because of superior gear.
The best skill and/or coordination, or team tactics, will win.

Just mentioning, because you have several teams that are low enough to join whatever bracket.
Can test PvP with a composition, and if you like it... they're a twink set.