When comparing Internet Explorer vs Seamonkey, the Slant community recommends Internet Explorer for most people. In the question“What are the best web browsers for Windows?” Internet Explorer is ranked 7th while Seamonkey is ranked 21st. The most important reason people chose Internet Explorer is:
Downloads safely, quickly, and nicely.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Downloads well
Downloads safely, quickly, and nicely.
Pro System built-in browser
Browser has many system related features. With Internet Explorer you can run certain types of files, without saving them in a non-temporary directory, or you can change proxy settings via a built in Windows dialog window.
Pro Works great with ruTorrent
Pro Can fluidly stream 4k video
IE 11 can fluidly stream 4k videos on Youtube without issue.
Pro Isn't a big target for hackers
Nearly all browsers use the same browser engine as Chrome, Safari, or Firefox; meaning they have the same security-holes as one of the big three. IE doesn't, it has has its own engine.
In other words, even if you find yourself on a website that tries to hack your computer: It's very likely that the the website will only be designed to hack the big three, and wouldn't be able to do anything to IE.
Pro Not just an e-mail client
Seamonkey is more than just an e-mail client as it is a full featured web browser as well. This makes for a good app to use for those that dislike having many different apps on their devices as it is a bit like an all in one solution.
Pro Auto imports setting from Thunderbird
For those that would be making the switch from the Thunderbird e-mail client setup is quite easy with Seamonkey as it auto imports all previous Thunderbird settings.
Cons
Con Out of date
Con Final version of the browser
Microsoft confirmed that Internet Explorer 11 (released on 2013, still bundled in Windows 10) will be the last version of Internet Explorer as Microsoft is shifting it's development focus to Microsoft Edge.
Con Windows only
Internet Explorer is currently available on Windows only. Internet Explorer was previously available on OS X and UNIX, but both of them have already been discontinued.
Con No browser extensions
Internet Explorer's functionality cannot be extended via extensions/plugins.

Con Not standard compliant
Con Problem rendering online Google Web Apps correctly
I.E. 11 has many issues with rendering Google Web Apps correctly such as Docs or Sheets. The landing pages for each has incorrect button placements and doubled icons, making the sites barely navigable.
Con It's slow and crashes a lot
Con Created By Microsoft
Con No reader view
Con Permanent CPU usage
Seamonkey permanently uses CPU (quite a few percents on a Intel i7). On a laptop this causes the fan to run (which make noise) and the battery to lasts less time.
