We discussed this a bit one the other thread. TML, sacu and nukes are obvious choices.
I changed both the t3 gunship and t3 bomber to use the armored t3 bot x emblem instead of the + because it was easier to see at a glance. The T2 and t3 gunships are especially hard for me to distinguish zoomed out but this small change helps.
Making some icons, a pixel wider, while subtle helps to differentiate tech level.
I would personally like to have kennel drone engies be able to have different icon from default engineers.
I plan to test the default icon set to see what pixel size starts to cause overlap issues, and to test different sizes to increase visibility without adding clutter.
I would also like to point out that some of ASI issues is that the white borders are just too pronounced in some cases and making them thinner worked for me.
Cptant. I put a sash over sacu. Simple but easy to spot.