Do some research dude, figure out what best suits your needs. People on a forum can't make the decision for you.

My choice would be the Denon because I like spinning platters.
Im a turntable guy though. Guitar center would be your best bet to try them both out.

I've used both alot and if your gonna buy 3700 you can get the 3900 for not much more.

I got the 3700, And had the 800 also.
You cant compare them, The 3700 has so many features that the 800 lacks, maybe the 850 has some of them, but still the 3700 owns them all.
Midi control on everything, Spinning platter that works perfectly and usb mode.
for the mixer, Ill go with a Rane mixer, amazing faders and control over the software.
About the 3900, I personally think theyre a waste, Its pretty much the same thing, with tiny differences.

@roth, ummmm tiny differences, have you used a 3900. i have both. huge difference. huge. i come from turntables so maybe thats why you think it isnt huge. the 3900 platter wise blows the 3700 away.

freestyle - i havent been playing on turntables regulary, but i defenitly tried them alot, and it all feels pretty much the same. i tried the 3900 on the store as well, for me i havent felt to much different. maybe a little tighter, thats all. nothing that worth another.
but as you said this i searched on ebay for the prices and it really doesnt cost alot. so ofcourse its better to get something newer. where i live they cost way more then the 3700.

You can speed up and slow down the platter on a 3900 with your hand or finger just like a 1200, try that on a 3700. not possible so really its a huge difference. They have bascially built a 1200 in a cd player. its not plastic feeling crap like a pioneer 800 or 850 or any of them.

Yes I agree the differences are huge......So huge that for the first time many pioneer cdj djs are now choosing the 3900 over the club standard cdj800,1000,2000s. The 3700 simply did not achieve this accomplishment. If you Google 3700 vs 3900, the overwhelming consensus is get the 3900 by current 3700 owners.

I dont care what anybody says after 25 years in this game denon has built the closest thing to a 1200 we have ever had in a cd player. period.

As far as the original question, I prefer the pioneer 800 over the 3700.

Im curious why didy?

True

Considering Ive been a hiphop/scratch dj since 1985 on tech 1200, you would think the 3700s would be the obvious choice. My first cd turntable was the denon 5000 because of the spinning platter and when it was time to upgrade, the choice was between the cdj800/1000s or denon 3700.
I basically never liked the feel of the 3700s while scratching and was able adapt to the feel of the pioneer 800/1000 platter much better to my surprise.

That makes sense. Im not some oh i hate pioneer i just like to hear the reasons. Djs like different stuff for different reasons. I just find the active platter for me is so normal for scratching but i have learned to scratch really well on the ns6 so i get it. You adapt i guess and if your good you can adapt to just about any piece of equipment. ive pre ordred the ddj-sx so ill be back on a piece of pioneer eq again. looking forward to it