You should check out BlackCoin - it is the original pure Proof of Stake coin and BLK PoS is the base for nearly 2000 (partially extremely popular) forks that are in the wild between 2014 and now.
Actively developed, features a qt and a js based wallet, stealth wallet, atomic swaps, colored coins (tokens) and much more.
[ANN] Blackcoin [BLK] | The Original Proof of Stake Coin | No ICO | No Pre-mine
BlackCoin Subreddit
BlackCoin at Giiter (remove blank as the stupid forum script finds giitter "suspicious": https://gitter.i m/BlackCoin_Hub/

Price is low compared to many of the BLK clones, as there wasn't any premine/ICO, no (hidden) reserves, no bribes paid to big exchanges etc.. pp.
Still going strong despite the rather low cap.