I have not personally been able to get GForce or Aeon to work with MC for many many years. I am able to launch them as
standalone visualizers (on Windows 10) but they cannot be launched/operated within MC's "Display View". Glynor apparently found a way to get it working per this thread:
https://yabb.jriver.com/interact/index.php/topic,133768.msg927127.html#msg927127. I tried setting things up exactly as he described, but it did not work for me, but maybe it will for you.
As Eve noted, ProjectM is a great option. It includes 12,000+ visualizations when you download it from the link she posted. If you already have your own folder with Milkdrop2 visualizations, you can copy/paste them into ProjectM's visualization folder and it will use them. Here is a thread where I recommend another Milkdrop2 option called Wallpaper Engine. If you already have Steam installed, you can download both ProjectM and Wallpaper Engine from there.
https://yabb.jriver.com/interact/index.php/topic,133935.0.html To me, Wallpaper Engine is 100% worth downloading whether you use it for the Milkdrop visualizations or not. For $4 you get an incredibly polished program with access to many thousands of animated wallpapers… for free! I downloaded/bought it 4 or 5 years ago and have never had to pay for any upgrades. I think the $4 covers the program cost for life. However, a downside of using your desktop (instead of a standalone window) means your desktop icons will also be visible while viewing visualizations. For me personally that's not a problem, as I keep my desktop 100% empty all the time.
I think Wallpaper Engine's
Butternchurn and
Milkdrop visualizers use much better shaders than ProjectM, and its colors are way more dynamic. But... ProjectM does give users easy control over switching to a new random visualization, or simply scrolling your mouse wheel to the next/previous visualization in the alphabetical list order. ProjectM however also has its fair share of corrupt and/or really bad visualizations (blinding nearly all white, while others are just black for the entire default 30 seconds) - this never occurs with Wallpaper Engine.
But like Gforce and Aeon above, neither can be launched via MC's Display View - or if there is a way, I don't how to do it. That said, there is one advantage with that however: if you use multiple monitors, you can use MC to show album covers/artist pictures on one monitor, and have ProjectM/Wallpaper Engine show the visualizations on the other, which is pretty cool for a totally immersive music experience.