This may seem a simple thing to those who have been on steemit for a while but choosing between 50%/50% and power up 100% can make a difference to what rewards you get for posting.
When the price of steem is low (drops to around 0.10 or below.) then 100% power up is far the better option as steem dollors payouts are really low because steem is worth less.
As the price goes up then the amount of steem and steem power on rewards decreases and steem dollor payouts increase so then 50%/50% option is the better option.
Even if you plan on putting everything into powering up just build up your steem dollers and buy steem if the price is low. (Hoping we don't see a return to such low steem value though.) or when you get a nice little nest egg of steem dollors.
Random image time from my PC...
Let's go with a bird.