I want to say that all of them work since pets have only received buffed in the last few patches. But since you asked for my Top 2, The Fluffy Squishy - Pet Conjurer & Will O Wisp - Pet Cabalist
And of those 2, Fluffy Squishy should be the most striaghtforward to build and Pet Conjurers tend to be naturally tankier, so it should be easier for your first playthrough. It is also my strongest build so far 
If Will O Wisp is the build you are interested in, note that it would need to be leveled a bit differently and then respec’ed later on.
You can follow the build diary in my guide for Conjurer & Cabalist (near the end of the beginner section of the guide) to see where to put points every 10 levels.
If you have any further questions, feel free to ask 