@Chevytraveller, I have to agree. I give it 4 stars, docking Softube a star for the rigid interface. Cherry Audio's Voltage Modular slays Softube's for ease of use. You can intuitively drag modules between other modules and see them automatically make the needed room in Voltage. This stuff is so obvious, which is why Voltage is taking off at breakneck speed. Also, their open module development is inspiring. I own both products, but if Cherry had come out before Softube, I would have ignored Softube. On a side note, I wish one of these developers would find a way to allow more than one set of inputs for inter-plugin routing though. All we'd need is a transmitter plugin to be inserted on any channel anywhere in the DAW that feeds many inputs of the modular plugin. I digress. But back to the main point: Cherry kicks the shins of Softube on modular plugin design.
I agree to nearly everything, what has been said here so far. Only that I would have got me Softube's Modular even if Voltage Modular would have been on the market earlier. I have both, and I use both. I've produced a series of 19 tutorial videos about Softube's Modular, and I've started with a series about Voltage Modular. There's one thing, one aspect I want to emphasize in this discussion: Softube's authentic software versions of great modules like Clouds, Korgasmatron II, Rubicon etc. They don't only look like the original hardware they even behave like it (to 99% at the least). And because I didn't have (and I still don't) the money to buy all these hardware modules, I was and I am very happy to have the chance to work with them using Softube's Modular. And, yes, it's demand on CPU is a terrible limitation (especially, when you're running a screenrecorder to produce videos about the product). The biggest plus with Voltage Modular is (besides the nicely loww CPU demand) the possibility to develop modules of your own (what I'm going to do next year after finishing some current projects). Just a side note: VCV rack is interesting as well, but I don't like the poor documentation of the modules (if there is any documentation at all), and the fact that it is like with chocolates (according to Forrest Gump): You never know, what you get.