Heavy stuff down low for handling. Stuff I won't need during the day down deep in the pannier. Rain gear and other items that I might want on short notice, on top.

Front panniers should weigh about the same, you do not want one front pannier to be significantly heavier than the other.

Tent poles do not fit in my panniers, they are strapped onto the rack. For convenience I wrap my thermarest around the pole bag.

Small multi-tool in pocket, not packed.