Honestly there is no "best" answer. Best is what you will work well for you every time you use it, personally I have no use whatsoever for a random orbit buffer. I do not polish or buff cars for fun or enjoyment I do it because I have to after painting so I use a aggressive compound after cutting the paint.
That being said the same tool with a different pad and finer compound and glaze produces a mirror finish, the catch to using a rotary buffer is they require a lot of practice to become good and safe with it. The safest rotary is a small variable speed electric with foam pads.
If you are willing to invest the time practicing the rotary is the way to go.
This one works well is very controllable but will break your arms and quickly become a hated tool. I have not used this in years, it got retired after 2 full cars and still sitting in the same spot.
On the other hand this little guy from Astro was dirt cheap and have done many cars without any trouble, it really is a good little tool.
The difference in size.
This is my main buffer, air powered and super easy to control and work quickly, I use the small electric rotary mostly for single panels with a smaller pad.