I've seen a lot of comparison between Urban Decay's Naked palettes and MUA's Undressed and Heaven and Earth palettes, and as I've heard rave reviews about MUAs palettes, I thought I'd compare my favourite Urban Decay product, their Primer Potion, with MUAs version.
Urban Decay's Primer Potion retails at £14.50 for 11ml of product, whereas MUAs Eye Primer retails at £2.50 for 7.5 ml.
They also both have doe-foot applicators, and this would be my preference over the new UD style as well, as this applicator is effective in spreading out the primer over the lid.
On the left, which you can barely see, is UDs primer potion, it has barely any pigmentation at all, and only leaves a slight sheen. It also dries quickly and so it isn't the easiest to blend it over the eyelid. MUAs primer is a lot more pigmented, and is so much easier to blend and spread, as it takes quite a while to dry in.
Here I have a comparison of eyeshadow over no primer (at the top), UDs primer potion (on the left), and MUAs eye primer (on the right). It's obvious that MUAs primer gives a much more intense pay off as opposed to UDs primer potion and bare skin.
I tested the two primers out under eyeshadow for a day (about 6 hours of wear) and MUAs primer came out on top, it kept my eyeshadow intense and vibrant all day, without creasing or fading away, and while my UD primer potion did this too, the colour intensity wasn't the same as with MUAs primer.
MUAs primer surprised me with how good it was, easily more effective than Urban Decays, and although you get 3.5ml less product than in UDs, but, being £12 cheaper, I don't think that matters too much.