While Gigasampler is a sampler (having no internal sounds and requires adding samples after the fact), I find it very usefull and you'll never have to worry about being limited to sounds, all you have to do is buy some more samples. Tascam, who recently bought Nemesys, the maker of Gigasampler, is having a sale on Gigasampler products through the end of the year. If you're considering getting it this would be the time. Food for thought.
I use Reaktor, Reality, The Pro-52, Waldorf PPG, and the B-4. If you want the most for your money and are willing to spend time learning it choose Reaktor. If you want instant gratification and dont have the time choose one of the others.
Reaktor is the most powerful and flexable program I know of. It is dozens of synthesizers in one package.
