I need some help building a good Siren

With so many Aegis shields and mid to long range enemies, the Yang Lee will open the door to ending the rangers quickly, especially if you are using bendies or radiation. The Hwangje class seem to not be performing as well or as sudden. The radiation hit hard on naked targets. This way you can work on taking out Erebus, Typhon, and Mars as primary targets

Last Stand wont grant much longevity these days, more worthwhile to run things like balance units, nuke amps, and maybe an immune amp, and advanced repair or phase shift.

With pilot skills, there are baseline skills to always have such as armor expert and road hog. The rest of your choices, imo, are pretty easy to lay out - if youre going to do a powercell related skill, only do dodger as this cooldown reduction can have a significant impact on longevity. I dont do beacn dependent skills, or skills that only give a five second boon to durability or speed or damage; seems a waste of a slot. So in my mind this leaves us with useful longevity skills such as mechanic and wonderworker, and skill that will enhance your damage output in general, not temporarily.