Good question Grover ... I will share my logic and planning ...
At the moment the highest weighted thing on the leaderboard is the medallions (collection collector). I've been waiting until just recently for the new avatars to come in so I wouldn't get doubles again when I handed everything in, which was successful. The plan is set into motion.
Overall I personally weight the enchanted items as what I should aim to get most of. At the moment I have 34 enchanted items. In the long run I should get better deals, get more money, better scores, etc. The enchanted items are worth piddly squat though, I'll need tons of them to make a difference. We know that a successful enchantment results in 1/3 loss of money so I spend my money on the market, getting items and losing less money per enchantment. Through the market I've gotten lots of items to help fill my collections as well.
Spend all money on items, get medallions, then enchant everything except one of each thing.
This is counter productive to being #1 on the leaderboard and there's also a very low chance of getting a successful enchantment (I must have lost 1,000 items on it so far). Future changes to the site will probably ruin everything for me.
AND CHUKBOY ... we are both now Adept since I spent everything and our rating is based off group progress, not individual tracking. :>