staking is also not that simple as it looks like
No, it pretty much *is* as simple as it looks. How about Neo? You don't have to keep the wallet open and running all the time, unlike all the other pos coins. And even if you do have to do that, it really isn't a big deal and it doesn't require much maintenance or attention.
most of the pos coins requires you to set up a system which can be online 24 7 for the wallet to run and act as a node
Yes, and as you mentioned one can easily do this with a raspberry pi that doesn't consume much energy at all.
Navcoin and pivx are two of my favorites in addition to Neo, and those are the only ones I've tried staking. I never earned much with Nav since I never owned much, but I made quite a few pivx. Unfortunately it's price has dropped so low that I wouldn't stake it now. Neo on the other hand has held most of its value over the past 6 months or so even tho it dropped a *lot* since its all time high.