Freewheels

Although the price of entry is high, getting a WI from the get-go makes sense...

1. they really are fit-and-forget reliable - I've gone through 3 or 4 and they never (like never) skip a beat
   
2. mine seem to last around 3 years riding in all weather and I only change them when the teeth are terminally shark-finned. I was lucky to get 6-9 months out of a Shimano MX30 before they went funky, so it actually works out cheaper in the long run
   
3. MX30's are quiet, WI's sound like a death swarm of bees - I get a lot less peds walking out in front of me as a result = less grief
   
   

YMMV and all that...