Originally Posted by
no motor?
Wait until you start wondering which side the one pannier should go on if you go that route......

What about that then!

I've always thought in a wobbly kind of accident that it would be better to have the extra weight on the ditch side, rather than the road side. But hey, waddo I know?

I use my "landing gear" side. That way the bike leans naturally towards me at a stop rather than away from me. It also means my first pedal stroke is on the unweighted side. My landing gear is my left, so a single pannier, or the heavier one if using two, also goes on the left.
Anecdotallly, in bad weather last winter I found that hanging an empty pannier on the left side seemed to make motorists give me more room when passing. It creates the illusion that I'm bigger, and adds that "bulk" on the side they need to miss.