Best product for Exterior Woodcare?

The soffits & fascias of my house need painted. They were previously coated with Johnstones Opaque in Burnt Walnut for exterior wood but the colour lost its sheen & became very dull within a couple of months. The painter suggested Johnstones Exterior Woodstain in Mahogany or Redwood could be applied after a light sanding but I'm not too confident this will work. He says its up to me - so I need some advice please? I want a slight gloss finish, & for it to look good against upvc mahogany windows. Any ideas would be much appreciated - thanks!