My personal experience is kind of inbetween. Analogue monosynths are great as a learning because you are stuck with what you have, and can't easily switch to another VST or scroll between endless presets. Their limitations force you to actually learn how to create sounds, and over time you get an intuitive sense of how to tweak each knob and slider just right in order to get the sound you want.
However, VSTs are vastly more convenient and eliminate the annoyances of tuning, physically powering and plugging in a large amount of bulky machines, losing previous specific sounds, and they give you the ability to easily tweak and edit previous recordings. However, you lose the immediate sense of close control over each aspect of the sound.
Ideally, what I would like is a physical MIDI controller with an exact map of my favorite analogue VSTs in terms of knobs and controls. My current keyboard does have a few a customization options, but it's rather awkward to map it to the VST each time, and it's not precisely 1:1 as there's not enough knobs, and they're not laid out or labeled in an intuitive manner.
Also advantages of physical instruments are that you map a mental model to the instrument itself and IF the instrument is built properly and has a good workflow after a while you don't need to look at it, muscle memory translates intent to an action, becomes more intuitive and the flow is uninterrupted. The experience is immediate.
On the other hand, physical synths take a lot of space, break down, are hard to setup if connected together, some require batteries to keep the settings and patches alive and the battery could sometimes be a pain to reach to and change. I had a Yamaha SY-77, which was amazing by the way, the battery failed and the screen was dim. I gave up attempting to replace it myself, it required taking apart most of the screws and the operation itself was a couple of hours.
I started on VSTs but I think i learned a lot more by playing with physical synths and it was way more fun too. I kept them always on and whenever I had an itch to play I didn't have to open a project, click click, choose the instruments, sometimes being phased by so many options that the itch went away. Also sticking with a synth that didn't seem promising at first proved to be very rewarding after all, I'd discover interesting setups that I didn't think were possible. With VSTs I had dozens but can't say I felt like exploring in depth, I had no favorite VST, they all seemed to sound very similar.
VSTS have advantages though. You come back to an old project and want to modify something and bam, everything is setup the way it was when recorded. You make a mistake and you easily go and edit out the mistake without re-recording. All in all I'd say to look at VSTs when you are more production inclined. If you just want to be creative and play and learn at the same time without so many stops to make choices, physical synths are a good investment. Physical synths and a physical mixer!
However, VSTs are vastly more convenient and eliminate the annoyances of tuning, physically powering and plugging in a large amount of bulky machines, losing previous specific sounds, and they give you the ability to easily tweak and edit previous recordings. However, you lose the immediate sense of close control over each aspect of the sound.
Ideally, what I would like is a physical MIDI controller with an exact map of my favorite analogue VSTs in terms of knobs and controls. My current keyboard does have a few a customization options, but it's rather awkward to map it to the VST each time, and it's not precisely 1:1 as there's not enough knobs, and they're not laid out or labeled in an intuitive manner.