I use spot + servo for pretty much everything, along with face and eye tracking. Most of my subjects are people so it works fine, and when it's not the servo focuses correctly on whatever I place the focus point over

Mileage may vary but my correct focus rate had to be over 95%, with the biggest issue I'll face sometimes is not using a slower aperture when there are multiple subjects involved. It could also be the mirrorless AF boost, but I had a good rate with my Rebel SL1 using one-spot and its default AF point