Genuinely believe with my whole heart that OSRS is the best RS has ever been for most players. Diversity of content is unmatched by any other MMO - there's something for every mood and intensity level. Whether you're looking to keep it simple and take it slow or push the game to its limits like players have been doing for nearly a decade since OSRS's release - the floor is low and the ceiling is near-infinite.
Also the resources available are better than ever. There's not a single question you're likely to have that isn't answered somewhere on the wiki, there are loads of really well-made video guides for virtually every piece of content, communities in the form of social clans or Twitch chats are - for the most part - super welcoming and accommodating.
Jump back in and see how you find it! All the stuff that made the game great is still there, just a case of seeing whether it still appeals to you as a person after such a long time!