Nstive Instruments have the best vst synths but at a price. There are plenty of sample hardware to download and test before you make a decision to purchase. I havent had any issues with any software so far but the I have a core i7 computer and watch my CPUs. The only issue I have is that there arent many single synth VSTs to purchase seperately and you have to buy a bundle which can be high if your only interested in a couple of VST synths.