Kontakt - With KONTAKT 6, you can sound like a snare drum, a symphony orchestra, or anything in between, from a universe of sampled instruments.
UVI Falcon - Sampler/synth hybrid instrument
Pianoteq - Pianoteq is a virtual piano that runs on your computer.
LinuxSampler - LinuxSampler - free, open source pure software audio sampler with professional grade features.
Magix Independence Free - Magix Independence Free is a sampler software that allows you to create any type of sound with its 2Gb library.
H. G. Fortune VST Synthesizers - Collection of VSTi instruments released as freeware on Archive.org