Can foam padding isolate better than spikes?

They are doing 2 different things; the foam is isolating the speakers from the floor, the spikes are coupling the speakers to the floor. The first act to keep vibrations from reaching the floor, the spikes to transfer the vibrations out of the speaker as quickly as possible. Either can work and which is best is case by case depending on room, speakers, taste, etc. As always use what you think sounds best.

I am currently decoupling my speakers from the stands using FIM isolators, which are two cups with a ball bearing between them. I subistuted better bearings from Small Parts for the stainless steel ones that came with it. Disclaimer, I am a dealer for these although I have never actually sold any. On my present system I like this the best but very likely others might prefer other methods, you have to try them for yourself. All I will say is that when 2 of my friends came over yesterday they immediately noticed a difference between this and Blutaking the speakers to the MDF stands as I had them previously. One of them said that the silences were now "blacker" than they had been and the definition of the music was better.