I would say that using Resil/DPS gear would be better for PvP if you 1v1 or have an advantage over other players (more health, 2+v1 favoring you, etc.).
For flag carrying and/or being a huge "LOOK AT ME!" in BGs, I would say PvE tanking gear wouldn't do too bad. The only downside to tanking gear is that you do less damage, but make up for it by taking more damage.
If you want to mix both (to, say, have alot of health and decent damage), I think having high Defense (500ish?) with lots of health and resil/crit/str/etc. could be effective.