Older versions are also usually the safest programm....I currently use SVP 11 but I've used other versions in the past as well. I have to honestly say that the differences are very minimal. Minor changes here and there... but the improvements do not justify the price. Get the earlier versions for a low price and you won't regret the purchase.
After Effects is probably the most powerful of all but is cumbersome and is mainly used for design of short, CGI, type clips and effects. For example After Effects could make you a very professional intro. Other than that just Vegas man. Amazing program and so easy to use, so user friendly. You can just grab the edge of clips and resize them so precisely and quickly, it's such an intuitive program.