In my experience, the really big ROIs come from investing in ICOs with low market caps. Some examples are LINK (4x-5x ICO price) and DNT (maxed at 24x and still at 5x ICO price). Obviously, lots of research has to be done to differentiate the good from the bad, but its worth it for the potentially huge returns. Even when projects are solid like Bancor or Filecoin, there ends up being almost no room for growth because if they evaluate themselves with 200+ million dollar market caps and proceed to raise that much, the price has nowhere to go but down post-ICO. Therefore, I'm only interested in discussing solid, low-market cap ICOs here. I'm going to list the top few choices I've seen posted here and elsewhere, and I'm going to keep this list updated per your suggestions:
Upfiring -
https://upfiring.com - Incentivized P2P file-sharing. Pretty unique and overall solid concept with a very low market cap. If the app is successful I expect to see huge returns - for reference, similar projects like Siacoin and Filecoin are valued at 20x-30x Upfiring's ICO price. I skyped with them over an issue I had at the start of the crowdsale and they were very nice/knowledgeable. Their crowdsale contract is also made with in such a way as to prevent people from losing their tokens if they accidentally contribute from an exchange or incompatible wallet. Solid project overall.
Airswap -
https://airswap.io - Similar to shapeshift and 0x, but with a few twists. The team is large and is serious about the project. They use a whitelist for their token sale. There's a lot of competition here but it seems promising - we're in need of a good token swap protocol, as none have really stood out as the best yet. Edit: Cap is bigger than I thought. Still a good project but less of a margin for profit.
Cindicator -
https://cindicator.com - Really an incredible idea, but far-reaching like Golem. Very low market cap for such a large team and project, and as far as I'm aware it is about to be reached. The predictive market AI based on staking tokens is an exciting idea and it will be interesting if it is implemented properly as a way to advise investors. They promote collective intelligence which blockchain technology is perfect for.
EnjinCoin - Cryptocurrency for gamers, a huge market. They have a small team (4 people, plus advisors) and are seeking to raise $25 million according to my understanding. Very well put together roadmap, whitepaper and website.
Request Network - "Raising 100K eth, 21K people in slack before they shut down whitelisting weeks ago, and backed by the top silicon valley seed fund YCombinator."
Ambrosus - "Combining high-tech sensors, blockchain protocol and smart contracts, we are building a universally verifiable, community-driven ecosystem to assure the quality, safety & origins of products." (Some serious credentials on the people behind this one)
Wanchain - Whitelist closed, ICO starts October 3. "Wanchain seeks to create a new distributed financial infrastructure, connecting different blockchain networks together to exchange value." ( A lot of people from Factom advising this project)
Grid+ - ICO starts October 30. "Grid+ leverages the Ethereum blockchain to give consumers direct access to wholesale energy markets. This decreases costs, shifts production closer to demand, and moves us all toward a cleaner energy future." (Backed by Consensys)
RedPulse - ICO starts October 8, Whitelist is already closed (I think?). "China’s economy is already the 2nd largest in the world in terms of nominal GDP, and 1st in terms of purchasing power parity (PPP). However, as a market for investment and industry participation, it remains incredibly difficult to understand. This disconnect presents a huge opportunity to platforms and services that can bridge this informational gap. The problem is made all the more challenging to solve by several critical circumstances."
This is just a few that I've found so far based on my own research over the last few months, and suggestions from others in the community so far. I have some other projects I'm looking into for November as well, but will make another post when that gets closer. As I said I will add projects to the list as you guys suggest them - let's sort through this influx of ICO's and find which ones are worth our time.