I purchased Gloomhaven after seeing so much fuss being made about it online. It's a steep learning curve but there are a tonne of resources available to assist new gamers to learn the rules.
The box is enormous weighing in at around 10kg, the number of scenarios and variations means there are 100+ hours of content (with expansions in development currently).
Game wise it relies on attack modifier cards instead of dice which makes things more interesting and a scaled difficulty level depending on numbers of players and experience.
A final note this is a ‘legacy’ game which means if you play the campaign you make permanent changes to the game (non-removable stickers, scrapping cards etc) so it can only be played through once.