I am new to advanced stats but these are some of the best resources I have found so far.
JFresh's Patreon: $5 a month. Includes Player and Team Cards and Tableau Workbooks that use Patrick Bacon's WAR model and other statistics.
Explanation of this WAR model: Wins Above Replacement — High Level Overview
More info: Patrick Bacon – Medium
Evolving-Hockey: Ton of good stats. Really nice platform with a ton of player and team stats, contract evaluations, and more. A lot is free but some requires a $5 Patreon subscription.
Link: Evolving-Hockey.com | Home
Evolving-Hockey.com | References
Evolving-Hockey.com | Glossary
Natural Stat Trick: Pretty much completely free, a few smaller things behind Patreon paywall. Awesome live game reports, With and without reports, Player stats, team stats and more.
Link: Natural Stat Trick
Patreon: Natural Stat Trick is creating a source for hockey stats | Patreon
More info: Natural Stat Trick - Glossary
Elite Prospects Premium: $9 a month or $99 for the year. Sure most people know of this site. Nothing crazy advanced here (as far as I have seen so far) but some neat features with Premium like Player Game Logs, Player Comparison, Agent data, Draft Center and EP Rinkside which has some awesome writers and great articles.
Link: Elite Prospects - Hockey Players, Stats and Transactions
Some other stuff:
Kaggle data sets: Haven't explored this much yet but looks like a ton of data sets to mess around with.
Kaggle: Your Machine Learning and Data Science Community
5-8 min game highlights: Sportsnet NHL Highlights YouTube Playlist
Line combos: Line Combinations: Daily NHL Hockey Line Combos - Daily Faceoff
Salaries and Cap Info: CapFriendly - CapFriendly - NHL Salary Caps
Win probs, player, team, and other misc data: MoneyPuck.com -NHL Analytics, Playoff Odds, Power Rankings, Player Stats
Other stats: QuantHockey.com