One of the things I think that makes the analog hardware better is its imperfection. You play two notes exactly the same but they never sound exactly the same. Also, I find the filters on hardware synths are far better. They are very smooth. No digital steps. You can very obviously hear this. As for valves, they are very organic sounding. It would be very very difficult to emulate that with algorithms. People have tried but the algorithm has to be incredibly complex. The plugins always sound harsh and nasty. I can distort the Vulture to hell and back but it never sounds harsh.
The reason I mention the Super Bass Station is that it's the first thing to get hold of if you want to try a hardware synth. These are a total bargain. It is apparently analog although it may not seen so. I had a problem with one of mine and I needed to replace a pot (hard to find the right one but luckily I did) but when you look inside, it has hundreds of resisters which suggests that yes it is in actual fact an analog synth. It's very small and lightweight and can be got really cheap. It was fairly regularly available on eBay but I see none on there now. The Juno 106 is another no brainer but that's bulky. It was the first analog synth to have full MIDI - very useful, in fact crucial really. You can get this Java app to totally control that synth from a computer either Mac or PC. It has digitally controlled oscillators. The digital control stops the analog oscillations from going out of tune. It also has digital presets. Again, very useful. It's the best of all worlds. It's also quite cheap because so many were made. These two synths are regularly used by William Orbit. Listen to any of his recordings and you hear that sound. Ray Of Light by Madonna is covered in Super Bass Station and Juno 106 sounds. The Super Bass Station is like the Roland TB303 but far far better. For those classic arpeggiated filter type sounds, it is awesome. It can do a few other things like filter another sound, not just it's internal sound.
I'm not anti digital. Digital synths do different things that analog can't possibly do like virtual modeling synths for example and no real need for separate hardware. The plugins are fine, like the ones in Logic Audio or Absynth so no real need for digital dedicated hardware. The digital synths are great for pad type sounds but not good for that raw sound. You don't get that incredibly fat and smooth filtered sound. Listen to Kraftwerk We Are The Robots and try to get that bass sound in software. You can't get close.