When comparing Prezto vs Oh-My-Zsh, the Slant community recommends Prezto for most people. In the question“What are the best ZSH configuration frameworks?” Prezto is ranked 1st while Oh-My-Zsh is ranked 2nd.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Lightweight
Pro Opt-in functionality
Pro No auto update
Prezto won't automatically update, which means that it won't ever start an update without your manual permission.
Pro Fork of oh-my-zsh
Prezto used to be a major fork of oh-my-zsh, and it was moved into a separate project to better focus on performance, simplicity, and customization.
Pro Great enhancements
The provided enhancements to zsh just hit the spot.
Pro Easy to extend
It is super easy to write additional plugins or themes for.
Pro Easy to understand config
The configuration is very well documented and makes it easy to edit.
Pro Super customizable
There are a ton of plugins that come with it for many common tools and OS's.
Pro Updates over Git
This provides a robust update mechanism with full version control. That means that no custom mechanism needs to be implemented for upgrades of the user profile. It also means that your own modifications can be preserved while still allowing upgrades. And it means that you can downgrade at any time to any previous revision if anything doesn't work right with the new version.
Pro Simple installation and updates
A user doesn't have to be particularly technical to benefit from oh-my-zsh. You run a simple command to install and it asks you if it may check for git updates on a regular basis. You give up a bit of control but you get a tremendous benefit for very little individual effort.
Pro Cross platform
Can be used by zsh on Linux, Mac or under Cygwin on Windows.
Cons
Con Slow
It works very slowly with some themes.
Con Major performance issues
It's not unusual to wait >1 second to initialize a new shell.
Con Installing/updating custom plugins/themes is manual
Installing plugin/extension that is not in the distribution (e.g. zsh-syntax-highlighting, powerlevel9k) requires git checkout and sometime creating symbolic link with adequate name (*.plugin.zsh, *.zsh-theme); also you have to remember to pull these repositories from time to time to update.
Con Updates interrupt your flow
The update check triggers on zsh launch, so if you leave your terminal open, you need to manually check for updates, or (most annoying) when you launch your terminal, sometimes you'll need to go through the update wizard before you get to your prompt.
Con Updates over Git
Because it updates over Git, if something breaks in an update you will need to use Git-fu to revert to an older version.