So I was thinking about getting some. Just ones with the Autobot and Decepticon insignia's. And I was wondering which ones look the best. Since there are quite a few options.
Depends what you are buying them for. Different figures/lines have different backings. For example Masterpiece use white backed symbols predominately.
The clear back insignias and the clear back outline insignias I think are the best. depending on the color scheme of the bot you are putting them on, I find they blen right in and it is hard to tell it's a sticker. Each figure kind of calls for their own though. Some look better with silver backed, some mirror, some clear, some white. All of the insignias are high quality. The mirror backed ones are a PIA to get off though.
Among my favorites are Tiger Track and Patroit for Universe Sideswipe and Sunstreaker. If you have a spare pair of them you can get 2 more characters in yout Autobot army. I also like the one that turns Universe Ultra Powerglide into Micromaster Hothouse.
I haven't bought any yet but I'm considering the Metroplex set. They look so much better than the ones Metroplex come with, which I haven't even bothered putting on him.
They rotate different free insignia label sheets with any order over $20. The current set is clear with white outlines symbols. As a result, I've rarely had to actually pay for the symbol sheets but the quality is very good. Two of the Generations/Classics sets I'd call "must haves" are Mirage and Tracks.
I've found their normal sized stickers are often a bit too large for my taste. The clear-backed mini symbol sheet has come in handy several times though. Most of the toys I've slapped badges on lately have been from that, or from the clear outline set. The silver backed symbols work well for very strongly G1 inspired toys, like MMC's Feralcons, but in general the decos these days go for tampo'd symbols, rather than stickers, so the clear back versions better match that aesthetic.
You are right about there being quite a few options where 'Bot/'Con symbols are concerned. I have used most of them and they all look great, depending on what color plastic you are putting them on. But for me, the most important thing is to trim off the excess border. It really helps give it a "finished" look. Of course, YMMV. Anyway, here are a few shots of the different types on different color figs... First up are some red/purple symbols w/ on clear background. I think they work better on lighter plastic or colors that contrast to make them pop more. That last one is on a blue background, but I actually did switch it to a clear background. You get the idea. Next up, red/purple on silver background. These especially I prefer with the edges trimmed off, though there are exceptions. They look good on dark or similar colored plastic. These are clear symbols w/ white outlines, but they also come in silver outlines, like the one I used on M3's chest. These look great if you want the color of the plastic or details to show through. And finally, here are some silver movie symbols. The eyes on the 'Con badges are slightly different then the standard 'Con badges, but they look really good on certain figs/colors. There are also a lot of cool insignias included in the fig specific sets as well, but I think I'm already pushing the limits with all of these pics. lol Hope these are helpful, and SORRY FOR THE PIC BOMB!!!
Both the clear background and purple (decepticon)/red (autobot) symbols (both mini and standard sheets) are an excellent choice. As are the clear background silver outlined symbols.