I have a bit of a hardware synth addiction and spend way too much time talking about them... but we're trying to get a new community started so I felt the urge to jump in and talk about them some more.
The two Nords are my favorites. The Wave 2 is great for beautiful layered soundscapes, while the Lead 4 can quickly go into unusual and striking FM sounds. I love both for how easy it is to dial in performance controls affecting as many parameters as you want in different amounts.
In the middle between them, I'm experimenting with Nina. It has so much potential and so many clever ideas, but first impressions were not good with buggy firmware. I had to put it aside to actually get work done, but I'm about to give it another chance. I'll probably be posting more about it later.
I only keep 3 synths fully connected and ready to use at a time, mostly because I don't want to buy an audio interface with more inputs right now, but it also reduces option paralysis a bit. Everything to the right is basically on standby to be swapped out with the 3 on the left from time to time.
The Prophet 12 probably gets the most use out of everything on the right. It's quirky and a little hard to find interesting sweet spots, but the few good sounds I've made on it (and even a few factory presets) keep me coming back. It's probably the most unique-sounding synth I own.
The Peak is my go-to for anything I can't do on the Nords, if I'm not specifically looking for the unusual character of the Prophet 12. It's deep/flexible enough for most things I'd want to do, without being too menu divey. I really want to upgrade to a Summit some day.
The Modwave is the deepest synth I own, but I kind of hate the interface. Some basic things like unison are buried several pages deep in menu, and it's the only synth here I don't feel like I fully understand yet. I'll have to find time to reread the manual again soon.
The SH-4D is the newest addition, and I've got mixed feelings about it. Multi-purpose buttons make it really easy to accidentally lose work, the mod matrix is missing a lot of destinations I hoped for, and "D-Motion" is probably the most pointless feature I've ever seen on a synth. Who in the world actually wants to pick up a synth and tilt it in the air while cables are hanging off it during a performance? However, it's pretty easy to dial in some really solid bass and pad sounds, and the drum kits are pretty good too.
I saved the Korg Prologue for last because I'm probably going to sell it. It's a pleasure to use and sounds great, but it's pretty limited without 3rd party oscillators and I haven't had a lot of luck with those so far. I also don't like waiting for warm up and tuning when every other synth I own is ready to go in seconds.
Aaand I probably spent way too long rambling about all those, but I hope it was interesting to someone.
I've been thinking about buying a Summit for some time, but I'm worried that its been around for quite a while - if I buy one, Novation are bound to release a successor a week later.
I have a Summit and absolutely love it. Default init patch is a bit clinical but the Diverge & Drift parameters really help there. Having used mostly soft-synths in the past, to me the Summit feels close in workflow to something like Serum with the wavetables, multistage distortion, high voice count etc.
I also wondered if they'd put out something new right after I bought one, but so far I've only scratched the surface of what it can do. Novation have also been good at supplying updates recently for the BSII etc, so I'm not too concerned there either.
I was about to argue that "newer isn't necessarily better", but honestly - if you don't need a new synth right now, waiting is almost always a better idea. Even if it's not a Summit successor, eventually there will be something you'll want more. The longer you wait, the more choice you'll have. I'd surely be better off if I had followed that advice.