Probably the best RB DAP - F40
There's just something about running video on a DAP that isn't meant for video watching, and won't play them OEM style, that just really pleases me.
My 40GB F40 has one of the most beautiful color LCDs I've seen on any PMP but it's isn't made for video watching with the OEM firmware. Just like my sansa C250, this F40 will play videos with RB and plays them very well, in fact. The little 2.2" LCD has an incredible viewing angle and is so rich in vivid color and quality that it just seems Toshiba really dropped the ball by not allowing OEM video watching on the F40...or F series.
Granted, you have only two format choices, MPEG-1 & 2, but at least that's very usable. With the LCD's 320x240 resolution, the image is quite beautiful and better than most of even todays PMP offerings.
I haven't yet tested battery life with video but audio...OGG, MPC...is over 30 hours.