- Define your list of what makes one device "best" and another device "not best."
- Arrange the items on that list in order of most important to least important.
- Select the device that, starting at the top of the list, meets the most criteria that are important for you before reaching a criteria on the list that is not met.
Based on the contents of the question, I'd say you prefer:
- More software options
- Less mobile
- Fewer software choices
It also appears you don't think proper color management is important enough to put on that list at all.
So for you, it seems the cheapest (you must define for yourself what price is considered "cheap" and what price is above that threshold) and lightweight (you must define for yourself what weight is considered "light" and what weight is above that threshold) device that also includes a software option that meets your needs is the device you want.
Many photographers would place proper color management at the top of the list and insist on a device that can be calibrated and profiled properly. For them price and portability are subservient to that requirement, at least to the point where they can not afford the device or can not physically move it around.
Many photographers would insist on a device that runs applications with features they consider vital, at least to the point where such a device is unaffordable or not portable enough.
Some photographers will place a premium on how long it takes a device to process the changes they make to an image. Others don't mind waiting a little longer to see the results of each adjustment.
Other photographers aren't as concerned with color management or other high level editing features. They just want a device that allows then to slap an instagram filter on it and post it to the interwebs.
Most current higher end ultra-portable devices are pretty good at displaying things already properly edited. What one sometimes runs into when editing on such a device is that colors out of gamut for the device are left in the image in overabundance. When the edited image is viewed on a calibrated device with a fuller gamut, the image will look different than it did on the more limited device when it was edited.