Looking for opinions on the accent colors specifically. I like the purple but am not sure if it's too dark. The turquoise and green are a bit sloppy since I need to strip them and redo the base coat anyway. The wash I used made them look dirtier than I intended.

Blue is my vote

The purple shade is nice! But its not the best match with the main color. Could you go with a more saturared base color more towards a grey/blue? It would make that purple pop.

The best way to do color tests is to take a picture and then digitally paint the model. I use Gimp! which is free software but you can use Photoshop or similar. This way you can very easily and quickly test endless color combinations.

*Edit: Below example of a digital color test done on a RC car I was deciding how to paint a few years back. I found a picture online of a white version of the car, then used it as a blank template to design the color patterns, before deciding which one to use. Finally decided to use the one in the bottom left. I hope this gives you some ideas