Good comparison The Best Portable Bluetooth Speaker | The Wirecutter
Very bad comparison, they don't know what they're talking about - there are many better speakers out there than the UE Miniboom for the same price or even cheaper.
Depending on how much you want to spend, the highest sound quality so far seems to have been achieved by these models:
- under 50$: JBL Micro II, TDK A12 Trek Micro
- under 100$: JBL Flip 2, Mirtek Bluetooth speaker or MEK MusicBox (cheaper replicas of the Mini Jambox that sound as good if not better), or even two from the above category connected in stereo
- under 200$: Denon Envaya Mini (hands-down best so far in this class), JBL Charge 2 (make sure you get the latest firmware update) or if you don't care about loudness that much and you can accept some bass exaggeration the Sony SRS-X33.
... and as you spend more and more you can find yourself looking at bigger and higher-quality speakers like the Infinity One and ultimately the Riva Turbo X (with the smaller and more convenient Riva Turbo S coming soon).
But this is if you want sound quality, as in correct reproduction of all frequencies as far as possible. If you want loudness above all else, sure, various things like the UE Boom, Bose Soundlink III or Beats Pill XL might work better for you. Or if you have a lot of need for water resistance you can look at the Fugoo or other stuff (though some of the hi-fi stuff I already mentioned also has splash-resistance so might be at least shower-ready, like the Denon Envaya Mini).
In general it's good to keep an eye on the sound comparisons posted on YouTube, that way at least you might get some idea of how your top 2-3 choices sound when played side by side. A certain Austrian gentleman has been posting carefully set up comparisons of portable speakers on his YouTube channel (clavinetjunkie) since 2014 and so far this seems to be the best source of comparison information out there.