I was actually using 4.4-r5. This seems the most stable version on my laptop. Wifi doesn't disconnect or need to be activated after logon. I tend to get wifi problems on later versions of android x86 with random disconnects, or needing to be connected after boot.
This version also has a display time out of "never", which later versions do not. This is a problem because the suspend/resume function does not work properly in Android x86. Basically if the laptop goes to sleep it can be a real pain to get it to resume again and if it does resume chances are the wifi will be disconnected. Therefore having an option to keep the screen on is quite important. You can get round this on later versions if you download a screen on app. (But really that shouldn't be necessary).
Also there is an option to power off from the top right settings menu. This feature is missing on later versions, and you have to hold down the power button to bring up the option to power off.
I found most software to be stable, I had a few crashes using the Chrome browser on some sites, but that could be because they are not optimised for mobile browser use. You can of course download any other browsers if required.
I also noticed the CPU light seems to be in constant use a lot of the time, though this doesn't seem to cause performance issues. It could be the way android caches data on the hard disk. If you go into settings and clear the "cache" it usually reduces the CPU activity.
Android x86 is definitely not for everyone, but it is certainly usable and this version is pretty stable with just a few minor bugs. So I would recommend you try this version if you want to use android on your PC but are having problems with the 6.0 Marshmallow builds.
Tried installing it on virtualbox. I wouldn't call the installation painful but surely it's not intuitive for the novice desktop user. When I got it installed, the mouse did not work, so, I had to go through the painful google account setup process with no mouse, I finally gave out.
Android x86 6.0-r2 is available now. The android desktop experience is surprisingly effective and will improve further with version 7.0 nougat which should allow multitasking support.
Keyboard and mouse support is actually quite decent in android, meaning you can use it without touch. You also have access to the Google Play store, meaning there is loads of software available.
I would imagine android is better suited to running on low end laptops or netbooks which don't have a lot of power, it is a mobile OS essentially, so is probably not the best choice for more powerful hardware.
If you have a touchscreen laptop and your hardware is supported by Android x86, then that would give you the best experience, as some apps really need touch function to work properly. Also apps that are designed to run in portrait do not scale properly or render sideways because a laptop screen is always landscape.
Most of these issues can be overcome by installing remix os, which is like android x86 on steroids! It has multi window and resizable windows support along with key mapping for touch only apps. So I would recommend remix os, which offers a more desktop like experience over android x86.