2019 titanium

Looking into getting my escape repaired. 2.0 engine. It slips when I am going from 1-2,2-3 gear shifting - it’s subtle but becoming more notable over the last few weeks. I’ve read possible fixes are changing spark plugs, drain and fill transmission fluid, I can get the lines flushed, or computer reprogramming.

My question is do I go to a certified ford dealer or local transmission shop?

It’s out of warranty by 2k miles for drivetrain anyways.