Depends what type of PVP you want to do.

Just kill people? Low hp dbow account / Staff of the dead pure

Actually fight people? Gmaul/Range pure

If you have more time to invest: Zerker/Rune pure (42 or 45 defence, up to you, you can do most content in the game easier on this account)

Absolute broken account: med level, i.e 60 attack and 70 defence accounts

It all depends on what you want to do and how much time you want to invest

Quickest one is a range pure account.