De-friending people due to their game choice seems a little silly. Game choice is subjective as everyone has different tastes. It is also not a very good indicator of maturity, with possibly the exception of something like Barbie island princes which is clearly aimed at a specific target audience.
I for one have enjoyed the entire COD franchaise and own all 8 games. There have been some lows in the series (namely COD3, WAW & BO) however in general it's widely recognized as a great series, the sales figures after all speak for themselves. That said, I do prefer Battlefield to MW series, purely due to it's more tactical nature.
Unfortunately however as per usual the minority of miscreants will ruin the experience for the majority as is the case some of the time with COD multiplayer. And the bigger the fan base, the bigger this minority will be.
I don't see anything good coming from a thread like this, these types of discussions usually only cause resentment and arguments so I'm going to close it now.