this question has been asked many times before and it's worth doing a search for the threads.
However to answer your question, I can recommend Sharescope on theb 80/20 rule. It provides 80% of the functions you need for 20% of the price and comes with a datafeed for a monthly fee.
I have Omnitrader, Metastock and Sharescope and I currently use Sharescope almost exclusively.
Metastock includes a powerful query language that is not available in Sharescope and OmniTrader is based on automated signals.
Sharescope gets five stars from me and unless you have special requirements (eg. realtime, custom indicators) the other packages may not be worth the premium.
Don't forget to consider AIQ in your appraisal too.