So I'm about to begin Dragon's Firefly 1C; however, I am having issues choosing between colors. The major issue for me is that I must use spray cans as opposed to an airbrush (Haven't invested in one), so I am having issues finding a color that will work correctly. I have been able to narrow it down based on research.

The first option is Plastic Soldier Company's British Warspray, this gives a nice and seemingly accurate color when sprayed. However, it's made for 15mm models, so I am unsure of how it will scale to 1/35. Below on the video, at around 3:25, you will see a Cromwell on the far left, which was painted with said spray.
https://www.youtube.com/watch?v=lEbC9BbjIIk

The second is between Tamiya's range of greens. Such as British Green, Dark green, and Olive Drab TS-5. The British and Dark greens tend to come out a bit dark, and TS-5 is a more last option as I would like to give the model a British flavor.

If any of you could tell me what's best or give me suggestions that'd be amazing! Thanks for reading!

Hello,
It looks good, and i don't see why not- however, I'm no expert! It looks good, and as long as you do some detail work and a bit of weathering it looks from the video that it should be fine.

If you really don't want to brush paint your tanks, those cans look like a good alternative.

Like I said, I'm only a beginner, and have had no experience from these paints!

Hope I've been helpful,
Nathan.

Well, the real things arrived in the UK in US Olive Drab, and after the Firefly conversion the affected areas were touched up with a "home-grown" OD called SCC15. So your Firefly really ought to have an OD look to it!

British SCC15 was designed to mimic US OD to save on having to repaint whole vehicles into traditional British colours (there was a war on, after all!), but over time it tended to fade to a greener tint whereas US OD tended to go slightly browner, so you might want to give a very subtle dry-brush of OD with a little extra green, just to get that tone. I can't be sure from just a video, but that spray looks like it should be ok. Remember - the weathering these things accumulated soon overpowered any subtlety in the base colour!

What makes a Firefly stand out (aside from the gun!) is things like the wavy white underside of the barrel, and of course the British markings.