I have worn creepers pretty much on a daily basis for the past 15 years. I currently have about 15 pairs of them. I stick religiously with TUK creepers...but not their new "low end" ones. I have tried a pair of those, and they suck....although they are pricey, I would definitely recommend to stick to their "high end" line that is made in the UK. Demonia sucks bigtime. They are not too bad in the comfort department, but they are made very cheaply and do not last.
I still have my very first pair of TUK creepers that I bought when I was 16, and they are still in good shape and I still wear them (I'm 33 now).
I have had a couple pairs of Underground brand creepers, which were very comfy, but the soles on all of the pairs split after only about 2 years of wear, so I steer clear from them now.