I like both equally, and I like to use them either separately or together along with 750 mg test, long esther. Here are my opinions about both compounds when you run them separately:
Deca- You blow up at the 4 week mark, and I mean you blow up like a water balloon on 500 mg deca (and, for example, 750 mg sust. I am a proponent of running my test a bit higher than anything androgenic like deca). The size is not quality however. That being said, it is mass. And if you are going for mass, run the deca.
EQ- You get quality gains and truly astonishing vascularity. However, in my experiences, it can take 8-10 weeks to really start working, and a lot of EQ is not legit. I have never been burned with deca. Early on in my AAS days, I was burned by fairly recognizable, albeit "mainstream" sources (*cough* alin *cough*) with fake EQ. I know it was fake because it was a batch of EQ that caused a bit of a firestorm on these here inter webs a few years back. Unfortunately, I also got burned a 2nd time with fake EQ from a separate "mainstream" source that no longer exists, so there is no need to out them. Having said all that, after making a fair amount of connections to better sources, I was never burned again after those two occasions. And real EQ is wonderful. I find that after 16 weeks on it, you add a layer of real muscle (as opposed to the fluff that deca adds, for lack of better vocabulary). And your vascularity and seperation is both highly noticeable and freaky.
Combination of the two- Imagine looking both bloated and veiny. This is the look that has people wondering what the fuck you are taking. A lean, 5'11'', 215 lb guy (6% bf) can appear to be 10-12% because of the puffiness the deca adds, again for lack of better vocabulary (how to describe it other than fluffy or puffy?), but then one look at the veins makes you realize that something else is going on.
Just my elongated 2 cents.