Speaker isolation or absorbtion - what is best?

As always with audio, it depends. With my old Focal Alto speakers they sounded best with spikes on couplers and Herbie's dbNeutralizer pads under the couplers. However, with my new Focal Scala speakers they sound best spiked directly into the floor.

There are no shortcuts, you have to try the options yourself. In this case, it's a relatively cheap experiment so there is no excuse.

All feets/ platforms will probably do something. Though, what they do, might be straighly the opposite to one another.
Generally speaking, spikes connects the chassis to the floor.
Which usually is no good idea. Springloaded or suspended often makes bass very dry and shy. Effect of this could be very high level of detail but a pronounced and not ear-friendly top. There are a possibility to use feets in conjunction with chassis drain-devices. But to fully determine which weight is not easy (on top of chassis).
However, it is not a bad thing to help the speakers get rid of stored energy as this tends to affect the overall sound very much. Some cases, cables choices become very different after and before the speakers are drained.
I understand what wonder about this.
I do not say this is your only choice, but you can look here for one choice.

Feets (you can order 4 instead of 3 per chassis):
http://www.entreq.com/default.asp?PageId=1923

Drain (mice and cone, same except for visual):
http://www.entreq.com/default.asp?PageId=1924

When i tried this, i must say, the effect is not at all small. A good speaker, can easily become extremely better sounding. (Mine is one example!)
This will most likely improve microdynamics, inner detail (as chassis vibration/ sound affects lesser), impact, start/stop-decay, bass nuance, air. The sound became clearer - less smear - less muddy. Intitially better speed (PRAT) and lesser sense of compression in woofer and upper mid.

This is part of what i notice in my system.

I hope that you dare try this and i believe the effect will put a smile in your face and ears.

I would try, from 4Kg's and up in weight for drain devies for full range speakers. I use Jumbo cone (one per chassis and four cat feets under speakers original feets).

At 700 a pop playing with absorbtion platforms/stands is not exaclty cheap, but the bottom line of the useful responses appears to be "try some alternative setups and see what works best". I will do just that.

Save some money. Try the Herbies products designed for speakers. 90 day trial period to boot so no risk. I use Adona platforms under my speakers, granite side face down. Works well for me on top of carpet.

Yes, good idea. It will give you perspective - which is good. I would say this works great, that i mentioned above. Better than changing cables, speakers (at times actually).
But all of us are different, and as it is too much bogus at the market, i understand some might think this is one of them.

Chime in if you find your key to all this!

Good luck:)