When comparing Pixaki vs Pixla, the Slant community recommends Pixaki for most people. In the question“What are the best pixel art / sprite editors?” Pixaki is ranked 15th while Pixla is ranked 36th. The most important reason people chose Pixaki is:
Speed, Onion skin, Reordering frame, etc.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Good section for animation
Speed, Onion skin, Reordering frame, etc.
Pro Easy to use
Pro "Free"
Considering what you get and in comparison with some competitors, you have to say that this is a pretty inexpensive piece of software. If you use it, you are free to make a donation. Otherwise Pixla is "free".
Pro Easy to use
Clean, uncluttered interface which is a must for a tool like this.
Cons
Con Only works on the iPad
Con Cannot import spritesheets
It can export spritesheets, but cannot import them.
Con GUI
The style of the GUI might seem a little outdated, but that is a matter of personal taste more than anything.