That's a nice find. There's some good stuff there.
Thanks for all the websites some nice looking stickers to try
Just noticed one thing on one site they had the fraction symbols that come in gold/silver/white/mirror and clear is there any hard and fast rule about which one would suit a TF figure?
Nope. Depends on the figure, both in terms of size of symbol and type. For instance, Reprolabels have faction symbols with the FOC characteristic glow effect on them, which works for FOC figures, but not so much for, say, your G1 bots. The white outline ones look good on dark figures. Gold ones won't look so good on figures with a lot of chrome or if the colour scheme doesn't suit it. Etc, etc, etc.
The only rule is that you have to like how it looks.
I think most logos used to be red/purple, usually with silver backing but sometimes with white, black or no backing. More recently there's been full silver logos with no backing for both factions. Some of the G2 autobots had logos in yellow or orange. The G2 FOC Bruticus and the new MP Acid Storm have emblems in black with no backing.
In general, match to your colour scheme, but beyond that you can do almost anything without being wrong.