I think the best mods are...

PDI glass or similar (Let the wars begin!). You literally look through it constantly. It’s THE best addition to any game, old or new.

Speaker Upgrades and external Sub. It’s what you listen to. I did most of mine with the Pinnovators coin door volume and headphones kit. It’s not the cheapest solution, but it’s very slick and easy to install.

Beyond that, it’s all eye candy, and will mostly not add anything to the play experience.

I COMPLETELY disagree with the Cliffy, Mantis, Mylar protector crowd. Who gives a shit if your pinball machine shows signs of wear?!! I have a HUO LOTR. Had it since 2004. When I clean it, it looks almost brand new. Most protectors effect ball movement in some way. The Mantis protectors do a slightly better job by being recessed in the scoops... but they are a PITA to install in many cases. You are unlikely to play your HUO machine enough to cause ANY noticeable wear.

If you sell the machine years from now, and somebody complains that there is slight wear around a scoop, or dimpling, or shooter lane wear... Laugh a hearty laugh, and tell them to get real. It’s a Pinball machine. You’re supposed to play it. It’s not a fu$&ing Museum exhibit.