What I use is this: Display Stand
It's plugin, very simple, only 1 speed, 2 directions, and fairly cheap. The only downside with mine and a few others is that after a while it creates a sound like the gears are struggling. I also bought a longer cord because the one it comes with is short. Mine still works just fine after 6 months, just beware that noise may occur.
I was lucky enough to get Hulk at Funko Hollywood and I ended up paying a bit more for Iron Man on Ebay just so I can finish the set.
Unfortunately, it wasn’t wide enough to hold the assembled set without the cake stand.