The best thing I've found if you have really dry lips is to have a two pronged approach rather than get one cream to do everything...
Firstly you need something that will really hydrate the lips and get moisture into them. I used to use a benefit lip cream that was brilliant - you could feel your lips rehydrating as you put it on. I don't think they make it any more - but it could just be using some of your day or night cream or even something like nivea on them if it's moisturising. Only needs a little - you don't want to drench them.
Then when that's sunk in, you need something greasy on top to seal the moisture in. If it also moisturises then that's great too. Best I've found is the lansinoh pure lanolin cream that is recommended for breast feeding but also can be used elsewhere. It's about £10/tube but I reckon mine last for at least a year if not two despite using every day.
Before I started using two different types of cream I had lips that were cracked and horrible and a real mess. Doing this really worked quickly - and these days I rarely need to use two types of cream - only if I forget for several days to put anything on them or get very dehydrated. Most of the time a tiny dot of the lansinoh cream on them before bed is enough to keep them really soft. Sometimes use it in the day too if I feel I need it, but it's not that often.
But even if you just try with your own moisturiser and your favourite 'greasy' cream, it's worth trying this approach.
I've tried so many different creams in the past - Carmex, Blistex, Body shop, burts bees, Elizabeth Arden 8 hour cream, and none of them are a patch on the Lansinoh cream.