In such a situation, small, rugged, good output, and a workday play life (8-12 continuous hours) with remote answering is the combination. The NFC paring is a nice touch as well, but regular pairing is simple and quick too.
Buy Now and Get Discount 50%
Not waterproof, but minor splash proof (like a oopsie with your Slurpee), it is a hard plastic shell with a rubber ring around it for good gripping. Also a lanyard slot on one corner, AUX In, Micro USB Charge port, and something I rarely see on a BT Speaker... a reset pin slot. I guess to quickly clear the NFC pairing?
Watch my video review.
See Product Details Here
Good overall performance, the volume and sound actually sounds about the same regardless if the speaker is facing up, towards you, or away from you - an important quality of "sports" speakers as well. All in all, when asked that question again - I now will say first off, "Omaker M4 is the one to look at."
I received this as a complimentary review product with the aim of hopefully elucidating features and drawbacks that may help you ultimately decide what fits your needs and budget best.