I consider Netsurf to be a beautiful and excellently well-done browser in its own right, so you can't go wrong with either.

But by comparison, Dillo is much more lightweight than even Netsurf (!!), much more brutalist, and a bit more idiosyncratic and the kind of texture and feel of how tabs behave, how you handle bookmarks, how you do searches. Dillo uses fltk while netsurf uses gtk3, and a lot of the resource usage savings in differences in vibe and feel come from that by itself. Netsurf is much more familiar if your baseline is standard modern browsers, and Netsurf does a better job of respecting CSS and rendering pages the way they should look.

Dillo can take a little bit of getting used to but it's a usable text oriented browser that I think is probably as good as it can possibly get in terms of minimalist use of resources, although at a rather significant compromise in not rendering many web pages accurately or using JavaScript or having an interface intuitive to the average person.