mp5's usually need accesories for them to look good so if your that kind of person that need to fill all the rails go for the mp5. If you like to keep it simple a redot for example then the sig552 is for you. what do you think would be more comfterble holding an mp5 or a sig? imagine playing a game what gun do you think you would be using if its a sig or an mp5? the gun that you chose is most likley the right choice for you. With the clear body on the sig you can see inside without taking it a part to notice some major damage wich is a positive in my books. Don't change ur mind on the gun you want to buy with anotherone as your mostlikly won't be as happy with ur purchase.
Good luck and cheers!!