This article is purely opinion based.
Almost all nations have good shops, but don't visit random nations to find good shops, there are always a few nations currently known that spawn trap, a list of them can be found here.
Nations with good shops (By what they sell)[]
Nations that sell god tools (from best to worst.)
Nubia
Pakistan
White_Russia
Kodiak
Everything else[]
Outback (wood, all forms of stone.)
Numidia (one of the best shops in the game)
Britain (many)
Bolivia (Iron / Redstone blocks, nether type blocks, Melons, Bricks, spruce.) (also Palau shop embassy here)
Svalbard (wood and natural materials)
New York (super wide variety + very good map art shops)