Ranked in these QuestionsQuestion Ranking
Pro Runs asynchronously
Warns of syntax errors as-you-type - you don't have to wait until you save your code or manually invoke syntax-checking (can be disabled).
Pro Lints as you type
Doesn't wait for you to save before linting, it lints the buffer, not the file.
Pro Being actively developed
Ale has a large, active community that keeps integration with language backends up to date
Pro Add fixers (prettier, standard...)
Pro Works with Language Server Protocol
Pro Works with minimal configuration "out-of-the-box"
ALE can be used almost immediately after installation. Some linters that need fiddling before they're usable with Neomake or Syntastic will "just work" on ALE.