Innova mids I have thrown a lot:
DX Shark - my first; thrown it a bunch in single disc rounds, great disc, still perhaps my best approach disc and owner of my 2 longest putts ever (80-100 feet).
DX Skeeter - a month throwing nothing but this would be great for one's game. When you hit it just right, it sails out there straight as an arrow and glides forever. When you throw with OAT or with any other flaws, it'll turn and burn pretty fast. Sounds like what I've heard from Comet fans.
DX Cobra - very fun disc to throw - I never get it to go as far as most mids, but it is super easy to control. I seems to hover out there, because it is slow and glidey.
Innova mids I've thrown on the field or a single round:
DX Roc - My first three shots all nailed trees off to the left of straight, so I had grip lock issues that day. I had a friend visiting from out of town last weekend who wanted to try disc golf for the first time. We visited the local pro-shop, Pipe Dreams, and he gravitated to the Big Bird DX Roc, and I didn't discourage him. I'm sure it is iconic for good reason.
Star Mako - Tried this out for the first time today, in field practice. I was expecting dead-nuts straight, and got it in spades. What surprised me was the distance I was throwing it, very long for a disc I've heard described as a longer putter.
Any of the above would be fine choices, as are others Innova mids I am sure.
My experience with the Shark let me know if you spend the proper amount of time with a particular disc, i.e. round after round with it alone, you will find its sweet spot which will become a money shot.