It is easier to use Darmanitan than Darumaka because it loses Hustle in favor of Sheer Force. This will amend your issues with its accuracy.
Between Darmanitan and Chandelure... it's very difficult to say which is better and I think they're about dead even. Darmanitan is available earlier and has more explosive STAB options, while Chandelure has stronger coverage, more bulk, and a better defensive profile. I think you should look at the rest of your team and decide whether you need an answer to Caitlin (in which case pick Chandelure), or a physical attacker that can delete most neutral opponents (in which case pick Darmanitan).