With the exception of an old Korg M900SP I sold when I was 18 and a SH101 I stupidly P.X.'d against a Yamaha CX5M when it came out, I've kept every synth I've ever had. Guess that means I don't really hate any of them.
That said, the fact that my mint Polymoog has never worked for more than a week is annoying. I don't use the old digitals too much, so I guess I don't like the D50, SQ1, DX7 and CZ3000 as much as I used to. The JD800 is a useable exception in digital, which I still enjoy.
I love the Andromeda, Voyager, Prophet 08, Oscar and Oddyssey. I don't use the A100 as much as I thought, but love the Technosaurus Mini Monsters and they interface well with both the A100 and a nice 5 Osc Elektor Formant I picked up recently. I love the Juno 6, but the JX8P or the Alpha Junos less so. The Matrix 6Rs came to life when I got the access programmer and remain favourites.
I love the OBMX - I find it hard to see the bad points it's notorious for - I work around them or use a different synth. I'd love more voices in it, but then it's £££££££ again.
Given my age, I got to play some of the big polys in the music stores in my late teens and early twenties, I have bad memories of the JP6 and haven't wanted one since. I loved the Rhodes Chroma and missed a great one which I regret. I found the Memorymoog overwhelming, but would like to try again some day. I just didn't get the Yamaha CS(x)M range or the Korg Sigma/Lamda/Delta range at the time (and couldn't afford them anyway). The Juno 6 and Polysix were great, and I eventually got both. The OBs were a dream to play, the JP8 never seemed to be in store (although I saw one in 89 for £450 in poor shape and let it pass). Oddly it was mostly through headphones in the stores.
When the big Polys were affordable in the post DX7 crash, I didn't have the cash to buy them, so would still love a Prophet 5, OB8/X, JP8, Synthex and a CS80 - but all seem unlikely with current prices. I have a nice Trident II which I like, but it never felt in the same league as the other big Polys (but can produce some great sounds all the same).
The Nord Lead 2 remains interesting, and even the supernova has it's modelling moments.The ESQ1 is also interesting, but I bought an SQ1 by accident first (doh!). eBay should limit the impact of drunk surfing and BINs!
I did manage to get a lot of old Monosynths before the prices got silly, so I still find surprises in the old monos too - CS5, Micropreset, Explorer 1, Jen SX, SH101, SH09 etc can be refreshingly creative, often due to their limitations. The Spirit still appeals, as does the Syrinx and ARP2600 - more empty dreams at current prices.
I have to say though, I play live with one keyboard these days - Nord Stage Classic and it's perfect for what I need.

What has surprised me is Nanostudio on the iPad, which I now use for most writing - Logic has become a "finishing tool" rather than a writing tool which surprises me greatly.
When I think of the rigs I used to play live with, I thank Nord for the Stage, and although the synth section is hardly complex, I can get a "live" version of most of what I need from the synth - so thumbs up.
Funny though, writing this I am back in McCormacks Music or Thompsons Music in the early 1980s playing with the synths, and it feels as exciting now as it did then.