In reply to iwhawley:
Hey, I have just done Everest base camp and did Annapurna base camp around 18 months ago. In all honesty, you would be better waiting until march if you want to miss the cold weather, but it does mean that there will be a lot more people. Everest, Annapurna and langtang are all well travelled, so have good facilities and western food.
Next time I go I will be looking at a more rural area as I like to get out and see the culture, something you miss on the base camp treks.
It will also depend what you want from the trek. Everyone knows Everest if you want bragging rights, but Annapurna was far more beautiful in my opinion.