Ah Gröna Lund. On my bucket list. It's definitely one of the better city parks. I just love how every ride is woven together: Jetline is one of the few remaining coasters designed by the legend Schwartzkopf and as someone who just came back from riding one of his masterpieces I'd love to ride it. Did you know that Anton always was the first to ride his own ride designs? Look at the guy, being happy as fuck: http://schwarzkopf-coaster.net/pictures/ES/anton-himalayabahn1.JPG I haven't ridden any Zac Spins like Insane, but what I've heard about it is that 50% loves it and 50% hates it. Kvasten is one of the better family rides. And with Vekoma's new train designs, even small children can enjoy the thrill. Twister is a brilliantly made puzzle, that thing goes all over the place and somehow doesn't crash into itself. Kudos to the Gravity Group for that: Did you know that there were plans to extend the park and build an awesome big inverted rollercoaster and a Star Flyer? Too bad they haven't received permission to do so. 
I love Gröna lund. Stockholm is quite close if you go by train for me so I've been there a few times. I am in the love group for insane. It is amazing. And I'm very impressed by your wonderful and complete knowledge.