Ahh Gary I'm having a similar problem at the moment
Although my problem is more with finding a detergent that will leave colours clean and fresh without bleaching the hell out of them.
I've found Ariel colour leaving a lot to be desired on that front of late. Asda colour liquid seems to do a better job, and can actually clean the dirt from the bottoms of my jeans, (which I always seem to buy too long). It's hardly perfect on the freshening front though.
I've got a 28 wash box of Daz for my whites, it seems to do an ok job, I have to use a long wash though, and go quite heavy handed on the dosing for bad stains, but I'm managing with it. It dosen't really compare to ariel though.
I'm contemplating going for Persil next time, had terrible experience with Surf giving lacklustre results, so I'll be avoiding that for a while. Can't really think of anything else to try apart from supermarket brands.
It's not on really that these brands charge a premium and give results that can certainly be improved upon. I don't see how they can charge more for Fairy than Ariel either!
My parent's are away in Germany this week and will be bringing me back some Persil megapearls, can't wait to give them a try, used them a few years ago when we lived over there but was still a bit of an Ariel fiend back then.
Would be interesting to see if there is some brand we are completley overlooking, which could actually trounce the lot!
Matt