Mes/Ran or Ran/Mes for anti-caster/overall versatility in PvP?

I've just quickly gotten a Mes/Ran through the newb area, and I like it, but I'm just wondering if I should consider switching the primaries before I invest too much time.

I think I'm leaning towards going mostly with the domination/marksmanship trees, so which primary attribute would benefit me more? I dont think I will have the skill points to put much if any into beast mastery.

How useful is the increased armor of the Ranger primary over the mesmer primary? That would seem to be the biggest advantage to me. How much energy do you lose out on with ranger primary, and is expertise enough to make up for this?

I'm planning this character to be anti-caster in pvp, but of course being good overall never hurts. I'd love to hear any opinions on this choice. Thanks for any responses.

Why are you making your PvP character in PvE. Don't waste your time, make a solid PvE character for PvE so you can get to your PvP much faster.