Since I work in keyboards in a retail store I have had the benefit of playing everything. Nord Grand and Piano 4 are lovely on their own but surprisingly not great as master controllers (the velocity curves aren't well suited to orchestral composing in my experience).
Komplete Kontrol S88mk2 is nice but very heavy weighting. Moreso than my Kurzweil PC3x. Same Fatar bed is found in the Arturia Keylab 88mk2. I used a Keylab 49 mk2 over the holidays and loved the weighted synth action by the way. Perfect for orchestral composing. Same bed found on their MatrixBrute.
Yamaha CP88 and CP73 are both very good as stand alone and master controllers. They also transmit MIDI and audio over USB. Yamaha P515 (with speakers) is also nice. A bit cheaper than the CP series.
Our store carries Dexibell and their S9 controller is a beast thanks to wood keys, motorized faders, unlimited polyphony and the ability to download sounds from their website. But it's very expensive (I dare say over priced given the competition at the $5000 price point).
Recently got in a Fantom 8 and the RD2000 key action is nice but heavy. I dig it however. Thinking an RD series might be my next purchase or else the A88mk2 (I don't care about aftertouch and I could put a NanoKontrol on top of the board for sliders).
I'm not particularly warm to the RH3 keyboard found on Korg's Kronos 73/88 as well as their GS-173/188 but I like it on their SV series. Not tried the D1 but I know a few people who bought them just as controllers.
Honestly, I haven't played a Nectar that I didn't want to chuck into a landfill. The action is horrible. No weight and cheap. The new Keystation 61mk3 have a nice semi weighted action. Build quality is another thing however.
M Audio Hammer 88 for the budget conscious is honestly the best bet. Simple layout, but really good action. Also leans on the heavier side but for $499 CAD, it's a steal. I think Mark Isham replaced his old KS88 PRO with it. It's solid.
As I said above, I'm waiting on the Roland A88 since I like its footprint (I have a small desk) but I'm not sure about the PHA-4 action. If its exactly the same as found on the FP10, I'm going to pass and probably get the NI S88mk2 since we get it for a ridiculous staff discount. Or if funds are low, the Hammer 88. I would prefer a more nimble weighted action like my current PC3x but that is more in the Dexibell/Nord price point.
I'm definitely with you on Nectar, I bought a Panorama 61 key when they launched and the key action was so noisy, you could class it as a musical instrument without even plugging it in, and the black keys felt like they were from a different keyboard than the white. Hated it.
I then bought a NI Kontrol S61, and it was just about acceptable. Lightguide excellent, keybed a bit spongy, ambivalent about the mod sliders, and really, with all that space, why no faders ! If I used it more I'd probably upgrade to the MKII with the proper mod wheels, but I don't so I probably won't.
My main keybed is a Nord Stage 2 EX which is a good compromise. It's not the best piano keyboard (take a bow Kawai MPII SE), but its compact and I use it in it's own right as a keyboard too. For composing I have some Pallet Gear faders sitting nicely (with velcro) near the mod wheel. I think the keybed on it is a happy compromise for playing piano & VI's. You have enough a a decent piano action that isn't too heavy for VI's most of the time.
However, despite its compact size and low weight, I don't like carrying the NS 2EX around when I travel, especially as my daughter uses it too, so I bought a Nord Electro 6 73 key for travel, and I love it. The waterfall keybed is a fab - it's only a shade larger than the NI S61, but those extra keys make all the difference. (No mod wheel - but I use the palette gear & velcro again). The Nord organs and EP's are to die for, and the one drawback is that when I fire it up, I can't help going into 'Ray Charles Blues Brothers mode' for half an hour, rather than getting down to some work.
I know you are thinking - that's damned expensive for a controller setup, but they are used as instruments in their own right quite a lot of the time too.
I used to have a Roland XP80 (really regret selling it) and perhaps it's rose tinted spectacles, but I remember the keybed and build quality being way superior to most modern offerings.
I went and tried the Nord Grand, which was nice but big, and the Kronos - which I found frankly to be awful for such a premium keyboard. If I were Korg I'd be embarrassed.
I think it's odd that most synths back in the 80's & early 90's were way better made than they are now, but it might just be me, as I think most things in the 80's were better, except perhaps some of the haircuts.
So I'll stick with what I have for now, in fact I think my next purchase might be a couple of those new analogue Behringer Synths that they keep popping out. By all accounts they are unfeasibly good for the money, and I think they will be tremendous fun. I have an irrational urge to buy an Behringer RD-8 drum machine too - but I'm resisting for now....