Transmission flush vs fluid exchange and filter change

I bought a used certified vehicle V6 in December 2015. I am assuming that the transmission fluids were checked prior to sale. It had 75,000 miles at time of purchase and in the last thirteen months I have put on 45,00 miles (120,000).

Although I have had no issues, and the vehicle is in excellent shape, I have not done any transmission, differential or transfer case maintenance yet, but I know it is time to address it. The owners manual is vague, and references use under the"normal driving conditions". I have been using the vehicle everyday for Lyft (150 to 175 miles daily) so certainly not "normal".

Questions:

1. At this point in the vehicles life, would you recommend a complete transmission system flush or just a transmission fluid exchange and a new filter? (Heard a lot of pros and cons to flushing; loosening debris, creating clogging, the reverse pressure process loosening seals, etc. vs having a complete cleaning for sustaining better transmission life).

2. In terms of order of importance for all the drive train components, can one area be addressed first or should everything be done at the same time?

Thanks!