First off, it's kind of silly to bump a post after 3 minutes - a lot of the mods (like me) prioritize threads on unanswered and unreplied to - so you just moved further down the list.
That's beside the point though.
The head unit is the centerpiece of the system and something you will look at and adjust every time you get in the car. That makes it both an important and a subjective decision. If possible, I recommend listening to the units and trying them out for a feel for how the controls and ergonomics work before buying.
Here is a comparison on those models and some comparables.
Essentially, you will not get good bass without either an external amp or a sub, but there shouldn't be significant differences between any HU in that regard.
On the USB flash drive - the Kenwood is limited to 65,000 some files which is pretty good. The JVC is limited to 4GB with no restriction - which might not be accurate, but that is roughly 1000 files - much less than the Kenwood. The JVC is a special purchase older model with Bongiovi sound processing. I believe Heat bought one and reviewed it here. Kenwood can be difficult to play all songs on a drive in random order, but will do it. JVC has 3-year instead of 1-year warranty.
Personally, I prefer and trust the Kenwood a bit more, but if I were buying today, I personally might go with a newer JVC (like the KD-A605), but some of those limit you to 25-letter file and folder names.
Hope This Helps!!!
Anyone else have suggestions?
2002 Ford Focus Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs
Of the 2 you selected, I would pick the Kenwood. I don't like motorized face HU's. In the world of electronics, by and large what fails most often is the moving parts. I'd like to point out that neither of those units has a rear USB input. My HU has both, but i only use the rear input with my flash drive. The front is convenient to plug someone else's flash drive in on occasion, but having something plugged in there all the time doesn't appeal to me. Seems like it would be tempting to would-be thieves. They make USB extension cables so you could locate the rear input into a glove box or another out of site place.
As a side note, Pioneer has a feature for .mp3 files called Advanced Sound Retriever(ASR). It compensates for the SQ loss of the format, and if listening to .mp3's is something you do a lot of, ASR is a unique solution that does a genuinely effective job, especially on lower bit-rate files.
BUMP
J Ro - Very good points.
I don't like motorized face HU's either. Also, I can't confirm this, but while the JVC has a 3-year warranty, I believe it is an older model and likely no longer in production - so while JVC would honor the warranty, I'm not sure you could count on getting the same model back if it failed 2.8 years from now.
My HU has a front USB port and in hindsight I would have preferred a rear one - mostly b/c the dash looks cleaner with a rear one. I used to be careful about unplugging the drive when I parked the car, but now I don't bother and haven't had any problem. Drives are so cheap now, that I don't think anyone really wants to steal just the drive - OTOH, having a drive sticking out of the unit means the unit can play USB so the radio might be a target, but now that lots of sub-$150 radios do that, I don't know that it's as big a deal as it once was. (It's also possible I've just been lucky).
I believe Kenwood has a similar feature to ASR (Supreme Setting on the MP342U) - JVC might as well (but I can't verify that off-hand, so maybe not), I know it isn't limited to Pioneer. Personally, I can't hear a difference between 135k-VBR MP3's and CD originals, but for really low-bit-rate (128CBR), I suspect it might help.
Thanks a lot guys! I checked out the Kenwood at my local car toys and will be purchasing the unit from crutchfield very soon.