I enjoy both sensations, but for me, nothing quite compares to feeling the solids passing my anal sphincter when I really, really needed the enema.
There's also that wonderful sensation when you finally get up off the toilet and your gut is feeling right.
When things work right (or close to right) all of these feelings are good in different ways, but when they aren't working right at all they're not so nice.
I don't like it when the enema injection just isn't going well and there's a huge urge at about a pint or so and nothing you do lets the enema move up higher. This is different from when you just have a full rectum - then the first enema might be small, but it clears out the rectum and the next enema goes in nice, with that rush of warm water ballooning out my rectum then working deeper inside, with the occasional urge or cramp to let me know it's working.
I also don't like it when the enema just isn't coming out easily. I like it when I have a good solid expulsion that brings everything out and that feeling of relief. It doesn't need to be all at once, it can be in a few good returns, but I don't like it when the water is stuck, burbling around, and coming out in little spurts now and then and generally not helping me to feel any better.
I even kind of like the feelings during retention, when everything is telling you to shit now and all your concentration is focused on holding everything in. Even when it's cramping there's a certain pleasant part because you KNOW that you will get the relief you crave soon, and also a little bit of showing your body who is boss and enjoying the roller coaster ride of the enema a little longer.