I use Comet. Color matched. For inserts, used orange for orange and it looks great, bold. To get distinction in areas where there are a lot of red and orange inserts, I used red and orange for important red and orange inserts (nice and bold, pops out), and pink (for red) and yellow (for orange) for the less important inserts.

Blue LED on blue insert again looks quite bold, great unless insert has black decal writing on it in which case the writing is a little hard to see. In this situation I used Come Ice Blue.

Also put Ice Blue under a Green insert. Resulted in a "Mega Man E-tank" electric blue kind of look. Pretty rad.