Which is better?

[Jallorn]

So yeah, which is better, the half-celestial template, or a major celestial bloodline?

[Glimbur]

In what context? For an ECL below 5, the bloodline is the only choice. At level 20, the bloodline is kind of 3 LA while the template is still LA 4.

Bloodline is a pile of small modifiers, with DR 5/Evil and Improved Init being the best of the lot. Template is more elemental resistances, fly speed, worse DR, SR, +'s to every stat, and the SLA's. By level 20 the SLA's make the template more attractive than the bloodline, but in mid levels the bloodline is better.

[Orzel]

Bloodline is a mishmash of random almost useless crap but only sets you back a little at if you are low level. Unfortunately most of the good stuff is at the end.

The template is better but it sets you back more until you get to ECL 4 or so ('cause you are way too squishy and you lose class levels from the start).

Low Level or primary divine caster, use the bloodline
Otherwise, the template.

[Dr.Epic]

So yeah, which is better, the half-celestial template, or a major celestial bloodline?

I'd say template only because I hate bloodlines.