The hardest wearing paint is an oil based gloss. This, in my opinion, is the best paint for a long lasting finish. That said, water based paint formulas have improved and they could easily be just as good as the old oil based paints. My favorite paint to use is Sikkens Rubol Satura plus, this is an oil based semi gloss. It looks awesome and is extra durable.
Farrow & Ball exterior estate eggshell is very popular. Its a dull eggshell finish. This paint doesn’t last as long as the gloss finish but you should still get a few good years.