I'm not against faucets but nowadays it is really a waste of time instead you have a lot of referrals working for you. If you have 1000+ referrals and 3 or 4 good paying faucet sites such as freebitcoin or moonbitcoin, you can relax and easily earn 0.01 and more per month. Better option is ptp sites as it allows you to earn passively. But all depends what are you doing with your earned satoshis. If you invest them into trading or lending, you can get much more and increase your earnings in upcoming months. Compounding is very strong method to increase your holdings in BTC. So, I would say that all methods are legit but:
1. Faucets are time consuming and tiny earnings;
2. Ptc sites - free of work method but earnings are small as well;
3. Signature campaigns - you need skills, ranking and hard to work to get your payments;
4. Trading - you need knowledge how to trade successfully, strong risk management, experience and luck;
5. Investing - you must have solid capital to earn just from it passively.
To sum up, the best method for me is compounding all my monthly incomes and put them into a trade. When you will reach 3-5 BTC balance (it takes not one month), you can put them into lending and get passive income. The more you have, the more you earn