If you just want a smart speaker in your room, the regular Echo is still an excellent pick, and while the Echo Dot doesn't sound nearly as good as the other Echo devices, it's an inexpensive way to put Alexa on any speaker you already own.
Generally strong sound with clear high-mids and highs; Alexa is powerful and functional; Bluetooth connectivity; Zigbee hub built-in
Not significantly more powerful than the Echo; Relatively weak bass; Bluetooth doesn't work with stereo pairs or Echo Sub