Advanced Chrome is a special fork of Google Chrome: its Custom Build version offers an improved Download System, integrated Flash Player and support for NPAPI, JAVA and Silverlight that were removed from Chrome.
The best part is that it's still compatible with Windows XP and updated (as of January 2018).
IceDragon is a browser based on Firefox and customized by Comodo. The official website automatically offers for XP users the version 184.108.40.206, based on Firefox 40.0.2: it works great, but if you want to use it the first thing you have to do is blocking the automatic update by going in Settings/Advanced/Update/Never check for updates.
If you don't block it, the program will search and download latest version of the browser, which is not compatible with Windows XP, and it will crash.
Lunascape is a web browser that handles 3 different rendering engines: Trident (Internet Explorer), Gecko (old Firefox) and Webkit (Safari).
Unfortunately it can be used on Windows XP with the Webkit engine only: Gecko seems to be no longer downloadable and Internet Explorer engine is basically unusable.