I like a certain balance of both. And I like quality, and having certain things given a bone to, in both areas.
I prefer an interesting linear game to a sandbox with nothing I want to interact with. Because if the linear game is interesting, then I enjoy what I'm essentially being forced to do, because they fit my tastes. But I'd prefer a sandbox full of a few things I want to do, than play a linear game full of things I don't want to do.
The optimal game, that has the most of what I want to do, would have a mixture of both, so it has the ability to balance and take the best of both worlds. And strong and gripping pace and feeling of moving forward. One that makes a person feel that their game is moving toward something. While giving frequent options to do other things and even get lost in them. You want to pull on the player a little bit. But if you pull too much they want an escape.
Tales of is a bit too linear. But is nonetheless my favourite RPG franchise. I think a great game would have everything I like about Tales of, but everything I like about a sandbox, as well. Also, the sad thing about "save the world" plots, is that they eventually leave you weary. When you want something epic, they're great. But over time, you just want to enjoy some slice of life character interaction, some to make you laugh or go "d'awwww, that's cute". Or even just a political conflict, something that doesn't say "impending doom of everything".
Or yet another way of putting it. You just want just enough tug and tension to keep you going and make you fascinated. A little bit of poison makes the heart grow fonder in terms of fictional realms. But too much poison, and you really need an antidote. An antidote other than not playing the game. That generally means lighter, light hearted, optional things. Things which aren't too stressful and don't leave the game feeling claustrophobic.