External unit Air Con - to mount or not to mount?

Hello again aus reno

What do people think about having a mounted air con unit on a set back/alcove brick balcony? I am leaning towards mounted rather than floor based for more floor space but not sure if it will be louder with vibrations on the brackets, or potentially some other issue I haven't considered.

Any pros or cons for either placement option would be appreciated from either ac tecchies or just people that have either of those set ups!

Thanks