Quoted from NicoVolta:Still on the lookout for the optimal LED for the pop bumpers. Haven't yet found the perfect non-ghosting LED in terms of hue and luminance.
I'm a big fan of Ablaze (Pinball Life) warm white frosted non-ghosting 1 SMD lamps. I use them in EM and early SS pop bumpers, backglasses, basically anywhere I don't see the bare bulb. They're the best warm white hue I've found. Most others have a trace of green or pink to my eyes. Pinball Life's site is temporarily closed for vacation, but here's a google cache of the exact product:
http://webcache.googleusercontent.com/search?q=cache:_eZv8HNWy8YJ:www.pinballlife.com/index.php%3Fp%3Dproduct%26id%3D3211+&cd=3&hl=en&ct=clnk&gl=us