Ultimate Ears BOOM Wireless Bluetooth Speaker
The UE Boom is one of the more recent entries in the market of ultra-portable rechargeable bluetooth speakers, and I have to say, it trumps all of its pre-existing competition. Its most impressive feature is its bass response: it has noticeably more thump than the JBL Flip or Jawbone Jambox, and doesn't sound muddy and smeared like the Beats Pill (or most anything with the Beats name on it, for that matter). It's still not very full or extended, and won't please an audiophile, but it's at least more dynamic and realistic than the competition.
The rest of the sound is actually reasonably well-separated and has acceptable detail for its size; even most wired speakers of this size yield to the Boom in terms of detail and realism. It distorts at high volumes, but the treble and midrange aren't unacceptably harsh, and never really sound downright bad; the JBL Flip, by comparison, can sound a bit shrill or tinny at higher volumes, and the Boom can play louder without distorting. Actually it just plays louder, period.
The Boom has easily the best battery life of any comparable speaker, squeezing about 15 hours out of a single charge; that's nearly triple what the JBL Flip gets. It also charges via micro USB, a huge plus considering that most smartphone users will be able to use the same cable that charges their phone. It even sports a water and stain resistant coating, along with easily the best build quality of any product in its class. The only even potentially useful feature that the Boom lacks is the ability to charge other devices, something rarely seen on these smaller speakers, and not much of a big deal anyway; the batteries on these speakers are roughly half the size of top-of-the-line smartphones, meaning it's really only useful for that one last call before your phone dies.
All in all, there's really nothing not to like about the UE Boom; if $200 is within your price range, and you're looking for something with all the bells and whistles and the best sound quality in an ultra-portable package, the UE Boom is it.