As a healer, which character is better? Or, which should I spend exp materials on first?
noelle if c1 but if you have bennette at c1 too then bentte
Bennett. Noelle doesn't even compare to bennett. Bennett provides very fast heals with an attack buff and doesn't require you to take up time for your main dps. Noelle requires you to use her basic attacks for a CHANCE (unless you're c1) to heal. You are losing dps with noelle, while with bennett you switch in, pop q, and switch out.
Bennet and it's not really close. Bennet is a support and healer in one. While healing he can greatly boost your attack damage. Though he does require C1 so I would take Noelle over a C0 Bennett but that's it
Noelle can be a good consistent healer if you have her at constellation 1. Otherwise, I recommend bennett. Bennett can only heal from his elemental burst, but it heals pretty fast and can easily be equipped with proper artifacts for strong heals.
Be sure to use him on teams with another Pyro character, or give him energy recharge artifact/weapon for fast and consistent burst uptime.