Part of the answer depends on your skill level, and what specifically you are looking for.
If you are simply looking for a "pretty" laser, I would suggest a lower power, unique wavelength laser. My personal choice for someone newer to lasers and laser safety would be single mode 488nm or 505nm and run it on spec at<50mW. That way you get a relatively safe laser you can enjoy without too much worry about using safety glasses etc.
If you want a bright beam, then high power 520nm or 450nm is they way, but then safety is much more important. If you going for burning, pure power is important, and if you are going for an specific experiments, then it depends on what exact use.