Liquidity is what matter most in must staking rewards coin, because most staking rewards coins does not have a lot of liquidity in the market which might leads to a plunge in the price . I make my investment criteria on crypto currencies also based on passive earning crypto coins because you can still earn some free crypto coins just by hodl most of these coins which makes a good investment @the4thmusketeer
I think Pundi X is an interesting project with good staking rewards, but it is important to make an investment into projects because you believe in the coin and not just for the staking rewards. Just my opinion.