Too many opinions, but capless when you can't see the led, frosted when you can.

I like Cointaker 170 deg bulbs for above the playfield

I like the super brights with the cap on them as they tend to be brighter and then clear cap for those areas under a plastic not seen.

Its really all subjective as to what looks best...

super bright warm white with a clear cap(retro) looks good to me.....

Your other options are Super bright warm white with a frosted cap, 2 3mm LEDs inside of a clear cap, Non ghosting bulb which is 2 smaller SMDs with a frosted cap.

Try ordering some samples and see what you like...

I use a variety and that is why I usually keep around $1k in LEDs on hand as it is always best to have the ability to swap around colors and styles. I use ct frosted, supers, pbl 4 led...really depends on the game and where there are going.

I prefer the ablaze non-ghosting ones from pinball life. They aren't super bright and don't make the playfield look too bright. I like the cointaker 89 flashers...those are bright, but I like my flashers to stick out a bit.