I agree with all the advice already posted. DPW folks are so wonderfully helpful.
Like you, I use both oils and acrylics, and have the same regrets you have with each of them. Water miscible paints have proved a good alternative for me, but (again, like you) I find WN Artisan and Grumbacher Max very dry and not comparable at all to buttery regular oils. In fact, many of my water miscible oil paintings look like my acrylic pieces. The difference is in the working; you have more open time to blend with the w-m oils, and they don't dry so quickly on your palette. They are not, however, as rich and soft as regular oil paints. As others have said, I believe that Cobra and Duo Aqua w-m brands are far superior, but haven't been lucky enough to get my hands on them yet.
I need to use a medium with my water-miscible oils, which include Artisan (WN), Max, and Lukas brands. There are several -- fast-drying, w-m linseed oil, and so on. It is very nice to be able to use soap and water to clean up, but with the exception of doing an initial sketch, I don't find using water as a medium a good idea.