This is not just my opinion but the opinion of a vast majority of lvl 50s.

Best Tank: Engineer
Highest DPS: Stalker
Highest range DPS: Esper
Most range: Spellslinger
Most mobility: Spellslinger

Worst Tank: Warrior
Lowest DPS: Spellslinger
Least range: Stalker
Least mobility: Engineer


All healers are strong but have different strengths/weaknesses.