This quora article by Mark Slee covers the advantages of hardware synhesizers above software synths.
In terms of digital hardware synthesizers, realistically there is very little they do that isn’t technically feasible with comparable software. That said, some of the advantages of digital hardware synthesizers are:
- Reliability. Most hardware synthesizers are more reliable than their software counterparts. Many hardware synthesizers made 15+ years ago still run completely fine. No driver upgrades, compatibility woes, etc. They just work, very rarely crash, and most can cold boot in seconds. Even with new products, hardware still tends to be held to a higher standard than software, which can be very important for live performance.
- Latency. If you want really low latency on a software platform, you need a quality audio interface with solid drivers, and you need to make sure other software does not interfere. You don’t have to worry about this with hardware synthesizers, which have dedicated low-latency hardware.
- Portability. Less of an issue with modern laptops, but it’s nice to unpack one device, then plug in power and audio, rather than multiple devices (computer, MIDI keyboard/controller, audio interface) with various connections.
- Interface. Hardware interfaces offer much more ergonomic and tactile controls than most software counterparts (though offerings like NI Maschine and some of the Arturia products are starting to get there). Of course, you can map software controls with generic hardware, but when push comes to shove, purpose-built tools often perform better. Play around with many synthesizers and you’ll quickly find that different instruments inspire different musical ideas, even if their technical capabilities are the same. Creatively, this is one of hardware’s biggest advantages.
- Performance. Related to the previous point, many hardware instruments are designed with performance, rather than production, as a primary design goal. Their interfaces and physical attributes yield more interesting and engaging live performances.
- Resale Value. Software holds extremely limited value – it is practically impossible to resell. Quality hardware synthesizers hold their value extremely well. If you buy used gear locally from its owner rather than through a middleman retailer, you can often re-sell at the same price.
In short, if you’re looking for raw technical capability, software will always be one step ahead, the development and release cycle is just quicker. If you demand high levels of simplicity and reliability, hardware still has the edge. Approaching the question as a creative, musical question rather than a technical one, there are many tradeoffs, each hardware synthesizer is a different instrument.”