I'm looking for some quality software instruments to add to Garageband (apple format, preferably).
GarageBand supports only one external plugin standard, Audio Units (AU) which is developed by Apple. Virtually all commercial plugins are available in AU, except some free, oddball ones.
If you want the ultimate quality plugin for synth, save all your money and get "Omnisphere" from Spectrasonics. That is the gold standard.
The other option is Zebra from u-he.com. There are a lot of amazing products from this company. Check it out
Although I have most of the Native Instrument stuff, I'm personally not a big fan of their synth, too plastic and Fisher Price sounding. The best synth they ever released was Pro53, now discontinued.
Also have a look at Albino, Alchemy and the product line of arturia.com. At the end, it is also a matter of personal taste, preferences (and $$$).Hope that helps
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