+HP/-def vs +res/-HP Titania...better IV?

See I use my titania as mainly support, to heal and buff my other horse units roy, lyn, and camus or Reinhardt. She is a 4 star +10 merged unit so her stats are a bit inflated but I believe mine was a +SPD or +RES I cant remember. My suggestion is to keep the +RES and "fix" her HP if you need to with a seal. Her def is already too low to have a bane and +HP may be nice but again you can just give a seal for a similar effect. Also here is mine to give you an idea of what you can do with her.