The M16 was used for the base of the Endor commandos blaster, and the STG44 was used for the Hoth Rebel soldiers. If you're doing an airsoft build, the A280, M16 base, would likely be one of the easier ones to do.
Stormtrooper blasters (E11) we're Sterling sub machine guns.
Boba Fetts EE3 was based off a Webley and Scott flare gun. His sidearm was based off a spear gun, as we're the Bespin Wing Guards (different model spear gun). Modified Lewis machine guns were used by sand troopers. The MG34 was another one used in Star Wars.
The prototype Super Trooper used an Uzi as the base for the auto blaster, but it's not the most recognizable blaster that most people would recognize.
There are cheap spring power airsoft Mauser C96 pistols available, and make a so so base. I got one on eBay for about $7. That would be a good place to start, as there are numerous DL44 kits for sale.
Here's an article about the real guns used in Star Wars.
https://www.washingtonpost.com/news/checkpoint/wp/2015/10/20/the-real-world-small-arms-that-inspired-the-weapons-of-star-wars/?noredirect=on&utm_term=.ea2fe7f09536