Walkthroughs for custom maps.

Which hero do you think is best for playing through the Wayfarer campaign? I don't mean for speedrunning, but in general. Yog has stronger attacks, but he'll move slower on the map, while Ciel will run at lightning speed at higher levels, which is good and will help with the playthrough. In my opinion, Gem is a bad option because she falls too far behind her companions by the time she's freed.

If it's not a speedrun and we're not in a hurry, then Yog wins 80-90% of all battles on the map.
Ciel is only for logistical functions: to go for distant artifacts, open a path, collect mines, reach a town so that the enemy doesn't have time to buy upgrades there, etc.
You yourself write "I don't mean speedrun," so the fact that Ciel runs faster doesn't matter at all. Let her run as fast as she wants, but Yog will fight the battles.
For a fast playthrough, all heroes without exception must have Logistics + Pathfinding so that they can run faster and further. There, by the way, you have to fight with all the heroes, based on the principle of who can reach where, just to be faster. In the 6-1-6 playthrough (or something like that), I carefully selected skills for everyone, and I had to fight with all the heroes based on the principle of "whoever reaches where, fights," and not who shoots better.