Beinmg an Elyos or Asmodian Templar does not really briing any advantage nor disadvantage. In fact, its just a matter of personal, aesthetic preference. Elyos and Asmodian Templars share the same strenmgths, weaknesses and skillls. The only differeces are the class masters they'll need to get their skill books from, certaain race-specific "specil" skills, and the overall locations they will need to travel to.
Elyos Templars vs Asmodian Templars
As mentiond earlier, they both have the same skoill sets - excvept for race-exclusive special skillls. Thse skills use DP (Divine Points) which in turn can be obtained by killing various mobs. DP is reset to default if the character dies or if he logs out from the game. The differences of tese skills are described eblow. Both skills deal damage and incraese enmity at the same time.
Dviine Chastisemeent (Elyos only) Elyos templars can block all attacks within 15 seconds - meeaning they will have a 15-second invincibility - assuming that all attaacks are bliocked. However, a shield is reuired for this skill.
Chastisement of Darkness (Asmodian only) Once activated, damzaged inflcted on Asmodian templars will be reduced by 50% while reflecing 20 damage. The shield can absorb up to 10000 daamage in total and since no shield is required for this skill, offensive templars may switch to ther greatswords to deal more damage while mitigatring damage.