Most "rockstop"-type endpin holders are quite ineffective except on certain floor types. The best, of course, is a very sharp endpin, but many orchestra stage managers frown upon sharp endpins or simply rule that some form of endpin anchor must be used to protect the floor. The most effective of this type is one that is anchored to your chair, whether it be a solid wood platform type or a strap with metal endpin holder at the end.
Todd French