3. University: (Alchemy, 2P): A fine card in its own right, this can be a trap, especially in decks with poor draw. It does, however, combo well with other cards starting with U, in that it allows you to gain free Upgrades. Being the only card starting with U that costs a potion, however, hurts University somewhat.
2. Urchin: (Dark Ages, 3): Urchin is difficult to rank, being the Peddler of cards starting with U. Indeed, just as you'd never pay 8 for Peddler, you'd never buy Urchin if you were trying to build a U-deck; rather, you buy Urchin to gain the powerful Mercenary, which starts with an M. Still, you can rarely ignore it, which merits its placing above University.
1. Upgrade: (Intrigue, 5): What can we say about this ancient card that was criminally underrated for so long that has not been said? If you're just using it for a copper trasher, watch out -- it may be too slow. A pro-tip: sometimes you have to stop buying upgrades and telling yourself you'll make them into golds on the next shuffle. Sometimes the time for gold is now.