I wanted a synth package to use with some of my music projects and I wasn't getting anything from any of the freeware sample packages so I opted for Roland Cloud SRX Keyboards. It's a huge package of 393 preset synth sounds which are customizable in a few different ways.
If you're used to working with analogue synths, you can start from the very basics with 4 voices each made up of wave generators, filters, envelopes, LFOs, all that sort of stuff. I've not done a deep dive into the various settings as I'm not really sure what I'm doing on that level.
In addition to the ground-up sound generation, you have a series of effects which you can add to manipulate your sound - delays, chorus, reverbs and other modulation, distortion and even amp sim effects. I think there are 78 in all (why is it always 78?).
The presets are grouped together in categories, making it easier to find the sort of sound you're looking for - electric pianos, organs, strings, lead synths etc. Some of the presets are best used in particular octave ranges so you may find one particular preset sounds good in octaves 4&5 but sounds unnatural outside that range.
In summary, there's a lot in this package with something useful for almost anyone. The presets are very and if you're confident in building your own patches from the ground up you can do that as well, or use a preset as the basis of your sound then tweak it to give it some individual character.
The only downside I can think of is that it can take a little time to navigate the interface and find the sound you're looking for. I suppose this isn't really a downside as such and should be considered a part of learning to use the software. The flipside of this is that once you've become comfortable with this software, you can expand your library with other SRX packages and will be familiar with the way it works straight away. With the Roland Cloud Manager software you've got the facility to plug into classic synth simulations as well. Overall, a good move from Roland.