"Best" is essentially hitting all the stat caps, which is possible for Miner and Botanist with the exception of the off hand item. FFXIVGuild has a page dedicated to this and it seems accurate. I've been using it, though I haven't melded everything just yet. Still, you can get to 408 gathering and more than enough perception without too much overmelding, though the extra GP will usually come in handy. It may also be worth noting that as of right now (on Behemoth at least) the only worthwhile item that a miner can gather that requires HQ gear with lots of materia is umbral rock (HQ) used for getting better gear, which in turn is used in theory to gather rarer things, but those rarer things are in such low demand that you'd do better farming shards.