The Micra 2210/2310 series are 1-watt Luxeon LEDs. Beyond that, it makes as little sense to compare 3W and 5W Luxeons as it does 1W to 3W Luxeons - they'll perform differently due to design differences between the 1/3W and 5W Luxeon Star emitters.
Short form: The Longbow series of lights is VERY customizable, and you could drop a 5W in there (or so I've heard) if you felt like it, and you could change the 123 barrel for an ECO tube and throw in L91 Energizer lithium AAs. Everything can be switched out, like the Alephs that McGizmo makes. The Longbows have a fairly white beam, from what I've heard, but you can switch it out for one of the other colored modules. Also, it's more a 'spot' than 'flood', from what I've seen here.
Q-III's a different sort of beast - small, compact, and designed to be a good 'every-day carry' without the customizability that the Micra or even the Arc 4+ offers. It is, however, fairly white and fairly intense, with great spill.
The CPF answer is to 'buy both', however. /ubbthreads/images/graemlins/grin.gif The Q-III's pretty affordable right now, and definitely cheaper than the Longbow. However, you lose all the modularity features and the booster head, which should again improve the throw on the Longbow. Up to you which you prefer, though I find my Q-III serves me well on everyday applications. It's not as bright as a Surefire L5, however. :/
But I can live with it. Maybe someday I'll get a U2 to get that 120 lumen feeling, along with some extra functionality. Or maybe a Longbow Max. /ubbthreads/images/graemlins/grin.gif