I know I'm not the first person asking this question, but I can't find a definitive answer anywhere. I'm looking for the easiest way to influence route selection based on user-defined preferences beyond what Valhalla offers. E.g. there's certain roads I like taking home, but they're not the fastest routes, yet I want Valhalla to suggest those first.

I see @kevinkreiser offered to write up something about that here #4240 (comment), though I couldn't find that anywhere, and I see the docs mention something called Factor Options, but then don't seem to document them further: https://valhalla.github.io/valhalla/api/turn-by-turn/api-reference/#costing-options

What are typically the best approaches to this? If it was just a single route in question the route could just be added as waypoints to the query, but if we're talking about a general approach of "preferring" certain routes/waypoints, it seems preferable to be able to tell valhalla which roads to prefer over others. Is there anything simpler than custom tags and forking Valhalla?