I completely agree - the IKEA dill mustard is quite delicious: the flavour is remarkably well balanced, and the mustard itself is creamy but still has a bit of bite to it.
My overall favourite mustard is Löwensenf extra sharf (extra hot) mustard. It's the one in the red bottle, and it's a good hot mustard - I find it's really hard to get a good hot mustard in North America, so that's my go to.
I did not find it outside of Hungary, yet, but there they have a mustard mixed with horseradish[1].
Since this type of mustard is unknown where I live, I tried to recreate it, but never achieved the same balance as in the commercial product, which is sad, because, in my opinion, it's a match made in heaven! It may be, that they use a milder mustard, than average, to balance out the hotness of the horseradish.
My overall favourite mustard is Löwensenf extra sharf (extra hot) mustard. It's the one in the red bottle, and it's a good hot mustard - I find it's really hard to get a good hot mustard in North America, so that's my go to.