I've played with Midjourney for awhile and just got my invite to DALL-E last night. One thing I think is really cool about Midjourney is the ability to give it image URLs as part of the prompts. I can't say I've had tremendous success with it, and it still feels a little half-baked, but I wish DALL-E had something along those lines. (Unless it does and I'm missing it). It's much easier to show examples of a particular style than to try to describe it, especially if it isn't something specifically named in the AI's training set.
DALLE2 isn't as flexible as the more open colab notebooks here; you can do "variations" of an image but you can't edit an image except through inpainting, so it's hard to generate "AI art" style images of the kind Midjourney and Diffusion are good at.
It also won't allow uploading images with faces in them.