Since composites sticks have become popular, you really notice NHLer's shooting with their sticks flexing behind them. This is also caused by a change in technique.
If you notice now, players sweep behind the puck more and lean down on their stick when they shoot. This is not a new technique, but with a composite stick that springs back to the exact same shape each time, you get extra velcoity on your shot.
This weight transfer is what golfers' do on every swing. They get their legs into the shot.
I am 6'2" and 210lbs. I have an Easton ST 100 flex and an old alumimum shaft which is an extra stiff. I do not recommend a shaft like mine or stiffer unless you really generate a lot of torque on your shot DURING THE HEAT OF THE GAME, not only in the warm up when you have 10 seconds and three strides to line up your shot.
If you are under 200lbs, I think a 85 flex is the highest I would go.
Second piece of advice.... shaft length.... get it right. This is critical.
Too long= no torque, no stickhanding.
Too short= great stick handling, good wrist shots, back aches, no torque on slap shots.