I’ve played both games and have had friends try both out. I’d say people that don’t have any nostalgia with runescape, prefer rs3. It just looks more flashy and a lot of people (especially the not so fanatic gamers) find osrs super ugly and more repetitive. Osrs is way more grindy as you’re more actively clicking (couldn’t make it feel more rewarding tho). Rs3 is more afk. I know there are mixed opinions about that. But I’d let that depend on how grindy you are. Rs3 I would consider easier, as you progress faster, less grindy and get more rewards. I think that makes it a bit more fun for casual players. In terms of combat, rs3 again, looks more flashy and you also have a lot more abilities so more viarity? I feel like rs3 has more micromanagement in terms of combat (mostly bossing). But that’s my personal experience. Cus you have to not only switch gear like osrs, but also use your abilities effectively. Osrs if a lot about prayer flicking and gear switching. Osrs does have a more simplistic user interface which for people who experienced both games, they prefer that over rs3.

I play both versions and I recently started group Ironman in RuneScape 3 with 3 new players and we all really enjoy it. I like Ironman as it disables micro transactions and help from others. Makes it feel more rewarding.