I have the UE Megaboom, which is a monster for its size. Unfortunately UE introduced unmanageable latency in their latest two firmwares. This makes it next to impossible to use it for live playing. For me anyway, maybe others can cope better.
Another vote for Charge 3 - will outlast the OP-1’s battery, and then recharge it for you, and still keep going! Also goes just about loud enough to use as a monitor in live gigs.
I use a Marshall Kilburn, and it is pretty great. Really nice build, good eq and gets pretty loud. I was playing my drum machine through it recently, and it was booming.