Using Sleven’s Primal Strike Warder as a base, I would go with Monk to go with your Shaman. It has passive RR, Attack Speed and more Crit damage to give your Primal Strikes more of an oomph. Monk has an on-demand heal, more resistances (at the cost of Elemental resistance which you should have plenty of), and a circuit breaker which should help you out if you need it.
Neidan is also an interesting choice, as it has Physical Resistance, Pierce Resistance (which the Warder is running low on), Damage absorption, Attack Speed, Slow + Stun resistance, and a passive heal.
Storm is a great choice, but a little points-heavy, which would conflict with your Shaman’s abilities.
I would choose those as your top 3. If skill points weren’t an issue, I’d say go with Storm, but Monk has a lot of value for the amount of skill points you can grant to it. Having an on-demand heal to go with your Primal Strike leeching is always going to be a big help, especially with passive RR to alleviate your focus from having to actively apply it.