To anyone who thinks they don't like "the look" of LEDs, and don't want to get into the nitty gritty, try 1SMD frosted warm white bulbs everywhere. The frosted part is important...I'm learning that more and more of the complaints of bulbs being too bright are from people using clear bulbs (which will cast harsh spotting on many plastics and backglasses).
There are brighter bulbs than that, but if you're a skeptic about color and brightness, a 1SMD (sometimes also called 5050...which is the part number of the size of the LED) is a great place to start. (SMD is Surface Mounted Diode, which means that the point of light is a square diode that points straight up from the surface of the base of the bulb). If you order from me (Comet Pinball), we'll be happy to refund or try and point you in the right direction if you're not happy with the outcome.
I never hear complaints about LED conversions that stick to frosted warm white. Most complaints about LEDs could be summed up as "user error", meaning: someone tried to get fancy and ended up going too colorful, or too bright, or used cool white (which we call "natural white") throughout (which takes out the warmth of the original artwork).
But obviously I'm a little biased.
Seriously though, when I acquire older games now, I really worry about the heat of the incandescents further damaging the plastics & backglass. That reason alone is enough to find an LED that works for you.