chain whips vary; some are rubbish, most are too short to use comfortably on anything that is remotely tight. Years ago (mainly for working on multiple freewheels) I got cheesed off with what I could buy and built my own. They are about 18" long, which is long enough to break the chain links that bear against the sprockets if you try hard enough. Needless to say they offer more than enough purchase for any cassette. Of those that you can buy the park tool is a close approximation.
The other part of the equation is the splined tool. If you have a bench vice then clamping the tool in position using the QR (the splines often don't poke through the lockring far and with some combinations of hub and tool, the tool can slip out) and then holding the tool in a bench vice is a good method.
If you don't have a bench vice then using a breaker bar works well. You can use a deep hex socket (so that you can still use the QR to clamp the tool in place) and a breaker bar with a head that swings over 90 degrees; this allows you to swing like a chimp without the tool trying to cam out, because the handle of the tool is brought back into the same plane as the splines.
There are plenty of tools that work some of the time, most of the time, even, but there are very few that work all the time.
cheers