I am afraid the only "true" investment for making some profit is holding your bitcoins and waiting for the price to rise.
1. Investing in Casinos
Nothing is sure, a big whale may make a big win and your investment is gonne (the worst case scenario,keeping your bitcoins in your wallet is a better option)
2. Mining Contracts
Its good that you have listed only the legit ones, but with those you will never make ROI (So keep your bitcoins in your wallet)
3. Lending
Not very much familiar with it but I have not seen so much success stories here either and the one who does, is only a small percentage you get (So keep your bitcoins in your wallet)
Just my idea regarding the investment sites of bitcoin.
As far as the investing in casino's sites like bitvest have limits as the global investment go's up are down the limits go up or down.
That also means you share the risk with other not just your self so say 30 people invested the same amount a big win would be split based n your share of the pot.
Which means when there is wins an you have more then others you will roi faster, many sites you have to wait 24 hours just to pull investment bitvest its instant.
Its your funds so why should you have to wait to pull them out or divest when you feel its not a good time to be invested.
But technically its not roi since you funds are always in your control its clearly profit or loses.
But in the end the house always win short term there might be loses but there is always someone willing to chase wins an degen.