Best source for bitcoins are trading and buying a good coin under ICO. My second choice is signature campaign.
As far as I am concerned hyip, refshare, mlm, cloud mining, other pyramid schemes and gambling can't be considered as a source of bitcoins, as you will probably lose them.
There are also more ways to earn bitcoins which are not mentioned in poll, for example lending, investing in gambling site bankroll, selling something etc.
to me i think the best way through which we can make good profit and make good amount of bitcoin is trading. through trading we can really get good amount of bitcoin, although there are so many other ways of earning bitcoin for example signature campaign, gambling etc, but still the best way is trading altcoin from where one can really get a good profit
Trading altcoins is the best source to earn bitcoin nowadays and most of the users are following the same method to grow their bitcoin in long term as its an permanent and long term way to earn bitcoins and on the other side signature campaign will give you limited amount of bitcoins for a limited time period as you can never depend only on it for a lifetime to earn bitcoins as you never know when signature campaign will stop paying its participants.