I've owned only the OEM top case and panniers that came with my k6 DL1000
They're okay. The locking mechanism on the top case didn't last. I could not find parts to fix it so I bought a new case. Expensive.
There are a myriad of excellent after market brands and choices out there. If it were me I would give serious thought to after market.
2018 1000XT, black. The Night's Watch. Givi engine bars, rear wheel mud guard, radiator screen. Givi V56 Litre Monokey topcase. Puig screen. Freeway Blaster horn. Speedohealer. SW Motech guards for R. brake reservoir, R. brake cylinder, exhaust pipe valve. Aprilia Tuono mirrors. GPR exhaust slip-on.
2006 DL1000, The Red Rhino. Gone for good.