Speakers with four feet are a PITA. For all my previous speakers, I had custom Sound Anchor stands made, and those guys know the benefit of a three foot base. There is no need for the constant adjustment. My current speakers came with Sound Anchor bases the manufacturer has made for them and unfortunately they have 4 feet. Fortunately, they are easily adjustable and lock into place, but still I find the need to occasionally go back and readjust, maybe because the spikes are drilling into the concrete just a little over time under the over 100lb weight. If you have an option, and you can make the speakers stable with only three support points, IMO that is the way to go. As to your question, I have tried SA cone coasters, Audio Point cups and spiked directly into the floor on my carpet over concrete and I think spiked is best. On hardwood, I like coasters or cups with Herbies Big Fat Dots under them.