From my understanding agility has a high ban rate, what other skills have a high ban rate? 

Hunter and Runecrafting in my experience.

but on the account i'm working on right now, i've made it to 40 Hunter in ~3 days.
Slow and Steady.

Well not only skill but a method has so called high ban rate. E.g. blast furnance for smithing, herb cleaning for herblore, oak chopping for woodcutting etc.

Highest ban rate for skills that I myself am aware of is wintertotd firemaking due to it being a money maker as well as levelling. Runecrafting for the same as before. Agility because it’s massively watched though the way around that is doing barbarian fishing, you loose out on the graceful pieces but get agility levels. Hunter for the same reasons as prior however I’ve found doing birdhouse runs is a lot safer than doing normal methods. If you look at it in terms of anything that has the potential to make you money is most likely going to result in a ban eventually. I have noticed that fletching is an easy 99 but thieving isn’t. 

Anything that gathers such as mining,woodcutting and fishing are all high ban rate

got a ban from agility in 2 days 3 hours a day.