NXT indeed was innovative when it started, the PoS algorithm was different from Peercoin's and the first with several characteristics of "modern" PoS, like a pre-selection of stakers and a rollback limit. They had a lot of very interesting project ideas, including smart contracts, but most of them weren't implemented. It was actually Burst who activated the NXT smart contract system, developed by CIYAM.

Ardor (the NXT successor) is still alive, has an interesting "child chain" mechanism, and does relatively well for such an old altcoin (at least it is trading above its 2018/19 lows), but the team made some gross mistakes imo like choosing a closed source license, and the promised "pruning" mechanism which would have provided an unique scaling mechanism still seems not to be activated on mainnet 7 years after launch (it seems still testnet-only and the source code hasn't been revealed for the testnet versions). Development is active though, recently a new version was published.