My perfect browser would:

 - Support gopher, first and foremost and allow me to change the look of directory listings
 - Have a feature to automagically group tabs of the same sites, like the Windows taskbar
 - This is almost obvious, but not track me or phone home at all without express permission
 - Allow me to actually add my search engines like Chrome and Chromium unlike Firefox which makes me add it from the store smh
 - Allow me to turn off CSS, JS, images etc on the fly to be lean on system resources and bandwidth
 - Allow me to change my useragent without additional addons
 - Have native userscript and userstyle support
 - Be like SeaMonkey and Netscape Communicator where it's a suite of a browser, mail client, web page editor etc.
 - Run well on bad hardware
 - Support Windows 98 (pipe dream I know)
 - Provide a Lynx mode/simulator