Volunteer or foster?

I’ve done both on and off for years, but I just moved back to an area where the need is HEAVY for any and all rescue help. My question is this: Would it be more impactful for me to volunteer in the shelter or foster at home? My work schedule is crazy so I only have the energy to commit to one or the other at the current time. Another note if it matters— I’ll be documenting either experience consistently on social media to spread the word. Any advice welcomed!!!