Its very boring to pick one of the small artifacts that keeps things trim, especially if its competing with a deck slot for a pet card
I'm over here sinning with T1 Entomb Sire of Insanity, T2 Animate Dead so I'm gonna have to pass on the "what is a fair return on 2 cards and 3 mana" question, because my perspective is way different than most here prolly since I like a little busted-ness here and there and I am a firm doubter of Tinker's appropriateness for non-powermax lists
with enough creatures you should be able to get one or two through for a huge sweep of damage
Lets move on to some less obvious cards in the same vein, possibly ones that dont require infinite mana
You can search your library for any dragon at instant speed, reveal it, and put it into your hand, giving you the perfect threat or answer depending on the situation
We're going to get so much value out of every populate card that they won't know what hit them