With the current GW2 today the combination of Valkyrie Armor and Cavalier accessories ,will be the way to go for Reaper since the 50% crit shroud trait and 2% crit per vuln stack.
Reaper can maintain 25 stacks of strength without runes, but there is no valk accessories the 1700 toughness of cavalier will be really helpful when you are in a tank. Cavalier is not a power but it can be like 90% of berserker damage with 1700 toughness and 24000 health.