Its still a personal preference for you. I'll give you information, but thats about as much as anyone can do, is to help you decide on your own.
- CoD: Ghosts
I'm not gonna lie, i was one of the first people to play the game and bash it for basically enhanced graphics on an incredibly similar engine. The people who give it a negative view are just tired of the game itself, ppl are just flat out getting burned out on CoD, its really that simple. The multiplayer to the game isn't horrible atm, and it will only get better when dedicated servers hit the game. I think Ghosts does a decent job at trying to add new gameplay modes to the game. Its the same CoD you grow up with, with tweaks to the game for past generations of it. If you want to play a new CoD, you should probably get this game.
HOWEVER, some (most) of the maps are large for a CoD game. Some have even compared it to a downscaled map for BF. 6v6 is also a pretty big negative for the game as well. The community hasn't gotten any better, as the game gets more popular parents will continue to get the game for the children and it will just make the community of game younger. Its the same CoD you grow up with, with tweaks to the game for past generations of it (yup posted this twice, as it is viewed as a positive and a negative).
Personally, you should get Ghosts on next gen if possible, it will only be a better game with a much more beefy system supporting it.You should also watch gameplay of it on youtube as much as you can to draw your own conclusions from the game. I hate saying dont trust the reports on the game, but sometimes you have to view the game yourself and draw your own conclusions before you judge it without playing it.
- Mw2
This really is a choice on your end once you think about getting Ghosts. You have played this game before probably back when it was super popular. Dont get me wrong, it still holds up as one of the better CoD's (kinda, but i still think CoD4 blows it away). The issue is that your gonna be running into a lot of hacked lobbies, cheaters, lagswitchers, ect ect ect ect. Simply because they dont really care about past games at this point. Just like how CoD4 is full of them, MW2 are as well. Its still stupid entertaining though.
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I personally play BFBC2 and BF3 more when BO, MW3, BO2 came out. Its just a personal choice of mine, but im currently burnt out on shooters. I dont plan on buying any new shooter atm, and im moving on to more RPG games, and single player stuffs. Already wasted 200 hrs on Skyrim =D, and i intend to finish my ME3 game, as well as start on Disgaea 4 cuz i heard really good things about that game. I'll eventually get around to Demon's souls and Dark souls. Hopefully before Dark Souls ill have the bug to play shooters again.
EDIT: Also, CoD games are always really expensive even after years of it being out. Shit i remember MW2 being $59.99 when MW3 came out, and still $40 when BO2 came out. If it has CoD in the title, your gonna pay out of your asshole for it.