Your suggestion for which plan Pak ?

HowdyI am near ready, I've added the many gmax aircraft to FS but can't decide which plan pak to use. I'm wondering if I could get some recommendations. Which do you think is the best. I 'd like busy but don't want to go overboard and have my airports brought to a crawl. I take it that I need to make a decision cause the aircraft title needs to match the aircraft.txt file.I have downloaded the Worldwide AI Project Sixth Edition, and the Worldai10a paks. If not one of these is there any others ?I was also wondering what happens if I don't have all the aircraft installed that make up part of these plans ?Will it substitute ?Thanks in advanceSteveCYYZ