ICOs vs. Airdrops
So Which Distribution Model Is Best?
Airdrops are harder for beginners to be a part of because they require you to own another cryptocurrency first. Most (if not all) airdrops occur by way of a hard fork attempt. In those scenarios you need to to have money to make money because you need to own the cryptocurrency that's being targeted for the hard fork to participate in the airdrop.
Using bounty campaigns, i.e., working as a promoter or advertiser for an ICO that earns you (as income) tokens from the ICO is an easier way for newbies ot get a stash of new tokens.
The most risky way to participate in an ICO is to purchase the ICO tokens with Ether or whatever. You need to be really confident of the business model if you choose to go this route.
You don't always need to have coins to participate in Airdrops, and I've actually participated in plenty of airdrops that only required you to make a registration in the airdrop, by providing your ether address. Some coins ended up with no value, bu others were quite good, and I still hold some, because they I believe those particular projects have potencial to grow further.
As for ICOs, I usually don't participate in them, because I prefer to see how the project evolves after the ICO finishes. There are to many ICOs out there, and even with research it's hard to pick one, because there are a lot of scams out there. I do participate in bounties for ICOs, since they are an easy way to get involved with the project.
As for the question of the OP, and think both methods are really good. ICOs normally provide more profit to project owners, since they work as crowdfunding. They are very risky, and maybe regulation will help in this matter, but they are very good options to get involved and support project development.
Airdrops are quite interesting as well, and they do have the potencial to provide some profit as well, because people will hold coins or even buy more coins so that they can maximize the amount of coins they will receive from the airdrop. When coins are freely given away, with no need to hold anything in order to receive the airdrop, it's still a good way of promoting the project, and allowing users to try the coin for free. If they see value in it, they will probably buy more and further support the project.