Yeah so basically the explanation behind the first loadout, which is actually the loadout i use the most, is that with the soda popper sure it has 2 ammo but a really short (around 1.4 seconds) reload time and can deal a TON of damage if used properly and you have good aim (I like to use low graphics for higher FPS and less lag as well as a high mouse sensitivity and lowered brightness to improve my skills and aim), and with the winger it's really powerful if used properly, sure it has smaller ammo clip but it deals more damage and gives you more mobility, and with the atomizer it gives you even more mobility as well as a minicrit if you land an air hit
so basically, loadout 1 is: less ammo, higher damage, more mobility