Highest end Denon would be the 5900 and the 5910 when or if it's out yet. I think the 5900 goes for 1500.00. Denon makes a much better DVD player than pioneer. The 3910 is also very nice. You should consider the Sony DVPNS999ES. Those are two of the more popular top end mass produced models out right now.
Denon seems to have a better reputation on audiogon and avrforums. They have great audio sound and very good video playback just out of the box. However the Denon universal players are respected enough to have a whole submarket devoted to modding them for a very high end sound. Not to many aftermarket companies if any, have interest in the Pioneers.
I love my Denon 2910 and I hear the 3910 is even better. You should also check out the Arcam Diva series. If by high end you mean REALLY high end then there's the Krell DVD Standard the Meridian range or the Ayre players to consider. Of course these start around $6000.00 and go onward to the stratosphere. If this is the area you're looking at could you also mail me $20.00 for the advice ;-)