The best replacement for pannier is trailer.

The best alternatives to pannier are rated as following:
★★★★★  trailer
★★★  basket
★★  saddlebag
★★  trunk bag

Your alternative for pannier is not listed? Suggest!
Speaking about pannier, one probably shouldn't forget about mudguard.

Other search terms related to pannier and their ratings are:
★★★★★ mudguard
You have in mind a companion for pannier and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of pannier in all years. Click on graph for more.
pannier
trailer
basket