I was also in that background where I no longer knew whether to test the betas as 16 colors or force myself to emulate it with PCem, or run the beta without Aero or special graphic features, even without a network, but here I will be recompiling which virtualizers to use when testing certain Windows builds.
For me, having a pleasant speed, and having all the features of the operating system active, is the best way to test a beta version of Windows (hardware specific tests do not enter here), so here is the list.
I recommend using VirtualBox, using OS Windows NT 3.x.
If for some reason it fails, use Other Windows (32-bit).
No, giving them specific names doesn't help.
Use the VirtualBox video driver that is compatible from NT 3.1 to Windows 7.
Get networking with the AMD PC-NET driver.
I only know that Virtual PC 2007 can run on certain versions, if in any case something fails you should use an emulator like PCem.
I recommend VirtualBox, use the video driver that is compatible from NT 3.1 to Windows 7.
I recommend VMware, with the default settings.
Get sound with setting the sound adapter to SoundBlaster 16.
I recommend VirtualBox, use it with Legacy virtualization mode without Nested Paging, with OS Windows 95, and without enabling ACPI, everything else by default.
You can get 32-bit mode with a generic VESA driver.
Disable ACPI on VirtualBox
VBoxManage modifyvm "myname" --acpi off
I recommend VMware, with the default settings.
Remember the driver that had to be installed manually with Windows 95? Use that to get 32-bit mode.
Get sound with setting the sound adapter to SoundBlaster 16.
It will depend on the build. Some builds work with VMware with 6.5-7.x compatibility mode without ACPI, if this is the case:
If it fails with VMware, use VirtualBox (if it fails, without enabling ACPI), everything else by default.
Use the VirtualBox video driver that is compatible from NT 3.1 to Windows 7.
Disable ACPI on VMware (Put this in the last line of the VM's .vmx):
acpi.present = "FALSE"
I recommend VMware, with VMware 6.5-7.x support, with the default settings, and disabling ACPI if installation fails.
Get 32-bit mode and sound with VMware 7.0 drivers.
I recommend VMware.
Get sound with VMware 7.0 drivers
For the pre-reset builds, with VMware 6.5-7.x support, with the default settings.
Get special features with VMware 6.5.2 drivers
For the post-reset builds, with VMware 10.x support, with the default settings.
Get special features with VMware 11.x WDDM drivers.
For these two, remember to enable 3D acceleration.
Some builds like 5219 may require you to use a VMware (the program itself) version minor than 12, using higher versions break the way DWM works in this build (flickering screen)
I recommend VMware, with VMware 10.x support, with the default settings.
Get Aero features with VMware 11.x WDDM drivers, remember to enable 3D acceleration.
With the exception of the Windows 8 builds that still have Aero, use VMware, with VMware 10.x support, with the default settings, using the 11.x drivers with 3D acceleration enabled.
After that, I don't think it makes sense to recommend virtualizers, after all they are recent systems, and any virtualizer should run them.
If you still want my opinion, use VMware with the default options.