if you could change one thing about btc, what would that be?
Would you make it safer?
How would you develop the btc trading?
I would make the satoshi to come back and explain to us why he has been disappeared and tell us more about bitcoin and make a documentary about the bitcoin.
I think, Bitcoin doesn't needs any change in it. But, if still need change something, sure I'll choose transaction without fees (even for a big transaction) and increase the the number of Bitcoins can be mined!
If there is no fee then the network would be abused too much, and the miners later will not have profit to run their mining rigs.