While I'll never know why the PSA card graded like it did, at least CGC gives me a little more insight with the subgrades
I would first look out for cards that have strictly better versions of them available
If the face-down card is a creature, it can be turned face-up for its mana cost
Honorable mentions out of the way, lets get to my Top 10 for broader Cube consideration
This is a strong equipment, not just on Frodo, Sauron's Bane (which is where I ran into it, and that game was not fun at all), and it's the type of equipment that will sneak up on a game of Commander and suddenly some player just wins out of nowhere with it
A major drawback from Cardhoarder, though, is that bulk cards and commons are always sold at 0.05 TIX, while GoatBots usually sells the same cards at only 0.005, meaning that you can get 10 cards for the price of one Cardhoarder common