Togekiss' STAB moves can hit Bea, Piers, and Raihan for super effective damage, along with some of Marnie's Pokemon. Chandelure's STAB hits Allister and Melony super effectively... which isn't helpful in a playthrough of Sword. Going on STAB alone, Togekiss wins.
The main problem with Togekiss is that you have to wait until Hammerlocke to obtain it, where you can trade for Togepi. You can find a Litwick in Motostoke Gym and a Dusk Stone in Stow-on Side, which makes the wait a bit shorter. In addition, Togepi is a friendship evolution, which can be incredibly annoying to manage. In terms of availability and evolution, Chandelure wins.
Overall, I would recommend Togekiss, as its STAB is more helpful for more of the game. In addition, the traded Togepi will gain EXP faster, making it easier to keep on par with the Trainers you'll be facing. Chandelure is definitely a top 3 Fire type in Galar, and I would recommend using both Pokemon, but Togekiss is the superior option if you can only have one.
Togekiss @ Wise Glasses
- Air Slash
- Hyper Voice / Tri Attack
- Aura Sphere
- Shadow Ball / Psychic / Flamethrower
