In Age of Triumph it's quite easy to get a lot of Legendary Marks pretty quickly, so buying a Vendor item for your lowest light items is always a good idea. Once you're at 380 there are tons of options for getting all the way to 400. Skeleton key chests can have predictable armor drops, so they're a great way to make sure your weakest item is ranked up quickly. Always make sure you're at max light when you recieve drops or turn in rewards!
I've been having trouble finding people under 380 light to test the min drops for some of these items. If you find anything is wrong in the table above, please let me know!