1. - yep, totally cliche here. Blue has counters, which are probably overall the best removal spells (stopping a permanent even hitting the table is huge, and don't get me started on instance and sorceries); green has very efficiently costed creatures and ramp. It also helps that probably my favourite card is Eternal Witness , which loves UGx.
3. - lends itself almost seamlessly to a wide variety of deck strategies - aggro, control, combo - you name it, gb can do it. Having access to Fauna Shaman and reanimation is a big plus.
If it's not obvious, I'm not the biggest fan - red does best in fast aggressive strategies I find, which isn't my playstyle. I'll pretty much only play red if I feel it's a strong deck in the format, or I'm playing it alongside blue.
I'm all about super-control in MTG. If you're able to stop my shenanigans, then there aren't enough shenanigans.
1st - - Best removal, reanimator colors and mana ramping, for whatever reason I've used these colors in concert to good results and I enjoy the strategies that can be employed with these colors.
It gets a bit murky after that and it's difficult to say what my "favorite" is.
Back when I was in high school, I used to write little quotes on the whiteboard of my chemistry class, little, funny things that I'd made up and attributed to an anonymous author. Just tiny things I found amusing. Some time near the end of the year, a substitute teacher game in, read it, and told us a quote she had heard from a 13 year old girl. I don't remember what it was, but the quote sounded deep and philosophical. Then I actually thought about it. I realized that the quote was actually meaningless, but simply couched in the language of philosophy and depth. And that's what your post is. It is meaningless bull**** that you said in such a way as to make it seem sophisticated. But just as a lab coat doesn't make you a scientist, language won't make you a philosopher. Only love of wisdom will. And until then, you will always remind me of a nameless 13 year old.
- and my favorite pair is 
