So far, I have been happy with a fairly simple corkscrew. I use the symmetrical lever kind. It's cheap, simple, and gives a food mechanical advantage.
Lately though I have had a problem with a couple of 20 yo wines, where the cork has become soft. The corkscrew, even when fully extended (levers vertical), doesn't go all the way into the cork. I've ended up pulling the top 70%, then pushing the rest of the cork into the bottle.
I've looked around for longer corkscrews, but they all seem "too short". At least, none is capable of fully penetrating the cork.
Any suggestions?