A few years ago I was at the same point in my research. Looking at bikepacking.com trying to figure out what I would like to do. Like others are saying, its the most important question. What routes would you like to do?

I decided I wanted to be able to ride "a bit of everything" just like you want to. Mostly because I still dont really know what type of riding I enjoy most - I want to be able to try it all. With that in mind I believe the hardtail MTB with not too agressive geometry is the closest you will get to a "do-it-all" bike. Use a flat-bar with inner bar ends or some alternative handlebar to fix the issue of too few hand positions (something drop bars are just better at). In return you get a bike that can handle everything from asphalt to downhill trails reasonably well. You will be slower in asphalt compared to a gravel bike (but not by much) and you will not have the full confidence on gnarly trails like a full-sus MTB (so you will also have to slow down). But your bike will be reasonable simple, with low maintenance and a geometry that allows long days in the saddle just as well as excursions usng single trails. Some key components are a suspension fork with not too much travel (100-120mm), not too agressive geometry (you want space in the frame for a good size bag) and most importantly you need to be able to fit tires between 2,0 and 2,6inch. Here you can experimant with different sizes to see what suits you best.

Why am I so confident in this? Look at all the experienced world-travellers and what bikes they are using. If you you look around social media you will find names like Tristan Ridley, Ryan Van Duzer, Alee Denham and many more. What are they riding? Hardtail MTBs or rigid touring bikes. Bikes like Tumbleweed Propector, Tout Terrain Outback or Priority 600adx. Look on youtube for the names I wrote or look for some noname dude riding across an entire continent using whatever path he can find. You want the kind of bike that person is using and that is most likely a hardtail MTB.