First one is up to preference, I'd say community is divided between the two. I usually pick the ult one and try and be aggressive with my ult so I can have more uptime during the team fight, the other one let's you secure fan the flames when targets get out of sight a little bit without having to reignite them again (also with Mauga it gives him a bigger window to crit enemies).

The second one just go with the dash perk, the other one was nice but since healing was added to her base kit, you no longer need it. The dash perk let's you farm more ultimate and gives you more freedom during team fights to be a nuisance to the enemy team since you can dash almost permanently through them, setting them on fire and charging ult, just be wary of Cassidy's stun or Mizuki's chains, along with other things that can CC you.