When comparing Slimjet vs SeaMonkey, the Slant community recommends SeaMonkey for most people. In the question“What are the best desktop web browsers?” SeaMonkey is ranked 27th while Slimjet is ranked 60th. The most important reason people chose SeaMonkey is:
Wraps all your internet stuff together. It's like it's Firefox and Thunderbird all wrapped into one, and it kinda is. It's the continuation of the project both of those were extracted from.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Fast and stable
Lower memory footprint and CPU usage than Chromium.
Pro Built-in adblock
Supports adding lists in ublock, adblock, adblockplus, and peerblock/peerguardian text formats.
Pro Allows for no tracking
Has advanced settings to reduce web presence footprint.
Pro Built-in download manager
Multi-threaded streaming download manager with resume functionality. Interrupted downloads will resume when the program is launched again; number of threads and download location customizable on a per-download basis. Actually downloads Linux ISO's from most popular distributions faster than deluge, utorrent, transmission, etc.
Pro Still compatible with Google's ChromeSync functionality
Sign in to back up your extensions and settings, just like always.
Pro Notes plugin available
Pro Easily customize to stop spying verified by OpenSnitch
Just have to dig into all the Settings and disable them starting with SlimJet search.
Pro Customizable options to add additional buttons next to the address bar
Optional buttons such as go to home page, reopen closed tab, go to downloads, go to history and many more.
Pro Built-in Youtube/html5/flash downloader
Allows for downloading both video and extracted mp3 audio, a la Youtube2mp3.
Pro Cross-platform, with zipped portable application available for Windows
You can still bring it with you on a flash drive, even when you're not on Linux.
Pro Screen recording tools built in
Pro Separate from Google's servers and tracking
Pro Integrated shopping and share-to-social-media function
Button is linked to cookies, so doesn't work if signed out (for security/privacy), and also doesn't include any additional tracking like a browser extension would (Facebook, Amazon, etc.)
Pro Verbose resource management
Has a setting to unload tabs from RAM and CPU usage after a customizable threshold number of tabs are open built in.
Pro Idle tab unloading and other advanced features not found in Chrome/Chromium
A lot more configuration options for everything from built in "share to facebook" buttons to options meant to enable optimization on low powered/low RAM systems.

Pro Full internet suite
Wraps all your internet stuff together. It's like it's Firefox and Thunderbird all wrapped into one, and it kinda is. It's the continuation of the project both of those were extracted from.
Pro Not bloatware
Pro Designed for usability, not looks
Cons
Con Still based upon Chromium/Chrome
Can yield to bloat if clogged with too many plugins and apps from the webstore.
Con Has some CSS issues on some websites
Has problems loading Sourceforge.com
Con Stores your history/settings into google servers
Con It spies on you
Con Bloated with unnecessary features
Seamonkey has a browser, email client, and even an IRC chat. Too much bloat! It doesn't do one thing, let alone do anything well. It should be avoided.
Con Looks very old and outdated
Con No Addons
not a single adblocker or privacy addon that was useful
