WDW before or after the cruise? The simple answer is: Yes. But it depends.
Our most preferred of all options is both. Four or five days prior, cruise, then 2-3 days afterwards. You can see WDW before the cruise - longer hours, more tiring, lots of walking. Then a relaxing time on the cruise. Then instead of sadly heading to the airport right after the cruise, there is the anticipation and pleasure of a few more days at WDW but taken a bit more leisurely than before the cruise. More time spent sitting around the pool, shorter days, just taking in a few of the things maybe missed before the cruise, maybe just doing more of the show-type things with less standing in line. Then I'm ready to go back home.
Secondary preference is WDW before the cruise and then the cruise. It's sad to head from the ship to the airport but at least your last memories are one of relaxation.
This year, the schedule will only allow cruise first and then WDW. But this will be our 10th time at WDW so we know it well and were there for 9 days last year and will probably go next year or the year after again. We intend to spend lots more time in lounges, late mornings, pool time, etc. We're meeting up with some friends who are local so will probably spend lots of time just sitting and talking. So although it's more go, go, go than a cruise we expect and intend for it to be more leisurely than usual.
So which is preferable? All of them but in different ways. It very largely depends on how you intend to structure your days and your time. Any combination can work - question is: what do you want to do?