hey vebmetal...you've been on the lookout for a HU for ages now. we have had a discussion on the Kenwood HU (4036)
here (Good speakers for Kenwood HU), extensively. Why all the doubts again !? FYI, again, YES, this HU comes with USB (front) and AUX in (rear). And it can read pen drives, memory card readers and HDDs.
The Pio 5050 is also an excellent choice. A friend installed it in a zen couple days ago and its simply brilliant ! Its got a 2-line display and looks very clean and neat. No silly dolphins etc. Excellent build quality too (the pics do not do justice). Reads a 2GB stick in less than 3 secs ! And its really easy to browse thru the folders/files on large drives as well. VFM all the way. The HU cost 6.5k.