I am a regular at TK Maxx, and have got some great sportswear, home wear, dresses etc there in the past. I was never really fooled by the RRP thing - I just decide if I think it's a good price and if I like it. You have to be savvy.
I was interested to learn about the TK Maxx own brands - I always wondered where all those random brands you only ever see in the Maxx came from! Have never bought them though, except for once I bought some Jobis shoes (which is apparently a TK Maxx own brand) and they fell to pieces quite quickly 
Brands I buy in TK Maxx include:
Whistles
Reiss
Celtic and company
Pringle (socks)
DKNY underwear
Various decent sportswear brands, Helly Hansen for skiing etc