If you are not sure what you want, I didn't. Check out http://www.ar15.com it is FULL of guys who LOVE those rifles.
But any question you ask there will need to include.
Why do you want one?
2. Home Defense
5. Just want to get one now while I still can.
6. Not really sure, I just want one.
I don't think that they are really piratical for plinking (~$0.32/round) , home defense (get you a good revolver or shotgun) or hunting (not sure if they are even allowed) but that is just my opinion and everyone knows that opinions are like A-Holes everyone has one and they all stink.
SHTF as long as you get a good one I think it would be a good choice. Once again my opinion. There are other weapons that will serve this role just as well, depending on the range that you expect for your likely scenario, and are less expensive. Remember that if this is your reason make sure you can also afford to spend the time at the range (time and $$). If you are not proficient with it it will just be a very expensive noise maker. Not sure what it costs over there but the only range here is $600 to get in the door and $100/year after that.
Want to get one now while I still can. If you have the disposable $$ I think it is a good move. That is why I got mine (picked it up today).
If you just want one because you have $1000 to burn and think that they look cool. It is a free country by all means if you can legally own one take advantage of your 2nd amendment rights, while we still have them, get one and enjoy it. :usaflag
If you do get one don't take any crap from the antis that say that no one "needs" an "assault weapon". Well no one "needs" a fishing boat, SUV, private plane, ....... either. I do not consider mine an "assault weapon" it is an "anti assault weapon" Hopefully if needed it will keep me from getting assaulted. And if they say that they are only used by criminals to shoot at the police ask them to show you the statistics. More LEOs have been killed with their own weapons than have been killed by a criminal wielding an "assault weapon".