Quality of pictures and equipment as well as flexibility for future

D7000 all the way, it's the best APS-C DSLR money can buy. It's built like a tank and has more features than you can shake a stick at.

The D7000 is better but it's up to you really... you'll get what you pay for.

Maybe wait a little more for the D7000 replacement or the rumored D600, a cheaper full frame.

Cheers!

If you have older Nikon autofocus (without SWM in the lens) lenses that you want to use, then D7000 is you choice as it has internal autofocus motor. 

You can still use your older AF lenses on D5100 in manual focus mode.  If this is not an issue, I would get D5100 and spend the money on better lenses.

Although D3200 is newer DSLR with higher mp sensor, the layout and the menu/interface are designed for beginners and may be limiting for existing/experienced DSLR user.

After D70....D90 is the best option. Considering D7000 is D90's replacement, Bob should go for D7000. D5100 is for beginners, D7000 is a better investment.

d7000 for a serious photography business; d5100 if u do not have old lenses and do not require cls as image quality for both of these are v close

I do not see from your post where exactly is D70 not satisfying enough for you. What kind of quality you miss? If you explain more why D70 is not good enough, it will be easier to answer your question.

Other than that D7000 is a more obvious upgrade path from D70, so if you really want to "upgrade" get the D7000. D7000 prices seems to be incredibly stable, I would not expect it to go down much. This is just a speculation though.

D5100. Same picture quality, half the price to invest in lenses.

This is not a fair battle.

Better image quality for next 6+ years :)

definitely worth the price and the all the controls and all the stuffs comes along with the camera!!

I'd recommend this camera for a long-term investment.

I am going to buy the Nikon D7000 myself soon, I have tried both the D5100 and the D7000... both are great but the D7000 is just better in almost every way! However I don't know anything about the price or life time for the D7000, it could be replaced soon. I am having a hard time choosing to buy it now or wait for the D600 or a D7000 replacement, I do not want to wait too long.

Someone had same question, D7000 offers much more functions witch you will need and helps you in your work.