Which floor to choose?

Honestly, I would go with whichever floor you feel you'd learn the most on. As a new CNA, no matter where you work it's going to take some time to get the hang of your job, and your coworkers will understand that. In addition, it takes a while even once you're an experienced CNA, to adjust to a new floor or facility. So, don't let that stop you. Accept the one that you will get the most valuable experience from.

The answer, as usual, is a matter of opinion.

#1, you'll learn the most on whatever unit will 'work with you' ---- give you decent training or a preceptor as we had in hospital, or friendly nurses who will help you through your beginnings of a CNA.

Having said that, I primarily worked in a med-surg/oncology unit. But, I floated to other units fairly regularly. There are different things to be learned in different units. Med-surg/oncology definitely had the most use of varying equipment. That is oxygen, suctioning, heart monitors, scd's, lots of drainage of bodily fluids, ekg's, plus going to the lab for blood and other items, virtually everyone was on an IV of some sort, and dealing with a wide variety of medications as well as regular post-mortem care. It definitely was the most complicated area to work in as far as the array of tasks. A large part of the shift was doing vitals. Post-surgical patients needed almost continuous monitoring for several hours.
Ortho was a distant second. You had to deal with some machines (continuous motion) and set up trapezes, but far less medication and IV's. It was still a lot of work on the unit to assist people who had various broken parts of their body, but not as much work as people coming out of surgeries every day.
The cardiac unit was the easiest. You will learn a great deal about cardiology, but the patients were mostly mobile and needed little care (as a generalization).
So, obviously, I'm pointing you to med-surg or oncology (if they are not combined as they were in my place).