Another one OP didn't mention is some sites pays you daily interest for keeping your funds there. I know about Yobit but this also comes with its own risk because should the site crash, there is nothing that can be done.
I wasn't aware Yobit offered such a thing, but I would never take advantage of something like that with an exchange like Yobit, nor would I keep a substantial amount of crypto on any exchange for longer than a few hours at most. Look what just happened to Upbit and how many exchanges have been hacked just this year.
Staking is a good idea but it takes time and same with open trades.
Depends on which coin you're staking. If you stake with NEO, for example, you're constantly earning GAS with it and you don't have to wait until you win a block like you do with other PoS coins.
OP didn't mention masternodes, but those are mainly for people with a lot of investment capital they don't mind tying up for the long-term. Having a Dash masternode is a way to earn Dash while you sleep. In any case, I think staking is probably the best way to do it. Lending? That's way too risky and you're always wondering if the borrower is actually going to pay you back or if you'll have to sell the collateral--plus you have to be careful about collateral scams and whatnot. It's just not worth it to me.
And you can't sleep when you see there are more than 10 people took loans from you that haven't paid yet.
Right, that's what I was getting at. I've only lent money a couple of times in the past 4 years, and each time was very stressful--plus I got scammed on my last loan to the tune of 0.3
BTC and learned my lesson from that.