Tammy, welcome, and thanks for asking our advice!
I've done a few smokes in the analog versions (1, 2 and 3), and a couple using Aubers and D-models (2D and 3D), so maybe I can help.
First, the advice on going with the 3, if in your budget, is very sound! Having used all models smaller, I can definitely say that the real "Q" estate of the number 3 is off the charts! If you want to smoke a big, whole packer brisket, the 3 is the only way to go! Full racks of ribs? ...child's play!
As for the D model over the analog controller? Having used both, pretty extensively, I would not go back to the analog controller! I like the ability to go above 250°, should I choose. I like the fact it keeps the box temp within a degree or two (consistently). I like the ability to program 6 different program "steps" into the controller, so I can "automate" my smokes. Bottom line? I love the PID controller, since I first used the standalone. Now that it's integrated, I would never go back to the stock controller!
I know it's a little extra, but my philosophy is "Pay once, cry once, because you'll be smiling the rest of the time!"