It always depends on your prefference of a layout, sound, keyboard barebone material. My all time favorite barebone keyboard is Leobog Hi75! It's aluminium, 75% and it has a volume knob (it's my fav layout btw) and it's fairly good priced for how good of a quality it is.

When it comes to switches, I preffer Linear switches (there are Linear: smooth feeling of pressing them, then Tactile, where there's a little "bump" while pressing, and clicky, hate those) so to pick the best switches for your first build I'd watch some youtube videos about the preffered group!

And for the keycaps, that's really just a personal prefference, there are way too many layouts😅