I’ve used the Anker SoundCore and SoundCore 2 in the past, and still have the SC2 here at home for times when I want to play music on the phone and not near the main flat sound system. But I’ve also just ordered an Ion Plunge to be using in the shower.
Larger than what I would have wanted but it has a battery pack and controls to change tracks whilst in the shower/bath
It also floats
But it’s whatever you’re after. I have found that the cheaper ones under a tenner don’t seem to last too long