I did the survey, but I want to expand here for discussion sake.
I pushed a little bit toward the linear side of things here because I'm sure that will be the less popular option given Minecraft is especially attractive to those who like to have total freedom. It's kind of a central theme.
But, if I want total freedom, I can just throw up my 85 favorite mods and go do whatever I want. I don't need someone to build that for me at all. If someone is building a pack for me to play, that pack should usher the user towards a certain intended experience. To do that, you need to step at least a little bit into hand-holding territory.
In a case like this, the freedom is still going to be there naturally unless the pack comes with a custom-built world to play in as well. You still build whatever you want. You still build wherever you want. And in the end, your goals are still your goals. But, where I DO want some guidance is in the progression of the mods themselves. Given absolute freedom, the majority will default to the paths of least resistance. IE, the same old cliches over and over again.
As an example, I never bothered with any Tinker's stuff because it just looked more complicated than it was worth. I went to start one day, but I didn't really know where to start, so I didn't bother. Until one day I tried out the Infinity quest mode (for like a day, sadly) and the first thing it does is walk you through the basics. I want that. But the tools themselves being gated helps ensure that as long as the pack goes on, there are still more things to discover. I can't tell you how many times I've started a pack with aspirations of experimenting with all these different power generation options only to stumble on something overpowered and forgetting about the rest that I blew right past.
Another thing is while I've gone through my open custom packs, with the idea being that I throw all these packs together for the purpose of exploring these different mods, not necessarily knowing up-front what each of these mods has to offer, I found myself often overshooting the effective range of the mods I wanted to explore. Having a quest mode move you through a natural progression helps ensure that you discover these mods at the appropriate time to get an appropriate reward for your efforts.
I don't know about straight linearity or hard-gating things behind other quests. I don't think that's necessary. A beginner quest chain to get started, opens up 3 - 5 chains that the player can choose between freely while you gear up for the next tier, etc.
Again the freedom is still in what you do with it. You can't hard-code in the requirement that someone uses these tools to build and awesome castle. That's all up to the player.
As for "grindy" recipes, I'm actually OK with this as long as there exists something like RS storage that I can use to help with the components. I like the idea of an item not just requiring this one item, but rather requiring you to figure out a way to automate the mass production of that item in order to use it for this crucial step. I don't think of that as grindy. If that's grindy to you, you're solving the problem the wrong way. It's not about taking the time to make 64 of that item. It's about the solution you come up with that makes coming up with a stack of them for crafting purposes manageable.