Hi, I am thinking to buy a MBP (I have been waiting for a long time...). I am using old iMac (bought almost 4 years ago). I do edit video for my family and friends a lot. I just don't know which MBP is the best in the market right now.... I was thinking buying 13" and also display, or 15", or 17" (is it too big and heavy to take with you anywhere???). Please, please give me some advices!! Thank you.