[experiment 626]

for fun games where winning/losing doesn't matter in any way to you having fun, go for the templars! they have a very iconic background and great imagery.

however, if you want to play at a slightly more competitive level, (and perhaps at the very least win as many games as you lose!) then just use your templars as regular space marines...
the templar list, while interesting and flavourful, is most definately the worst list to actually play! (barring pure grey knights who aren't ment to be a proper 'army')
the rightous zeal rules are crap and any decent player will use them to have you run off where they want you to, while the mixed armour rules can be used cleaverly to easily bring your squads below half strength if you take too many neophytes...

cheers!