Nikon D90 at 300mm or Megazoom camera at 700mm?

Which option out of the two would give me a better image quality?

1) Nikon D90 + Nikon 55-300mm VR lens. Take an photo at 300mm and crop the image to have the same view as in the next option

2) Sony Hx100V or Canon SX40: Take an image at 700mm without cropping at all.

Thanks

Added (1). Thanks a lot for the answers… I already have an 18-105mm lens.So, the wide end is fine for me until I improve my photographic skills (and my budget), but I also wanted to have a good tele coverage to take pictures of birds. Since I'm an amateur photographer, I won't go for a huge lens.

Thanks to the bigger sensor, the D90 would probably edge it.

The nikon has a bigger sensor advantage so it will give better detail. Why would you want to zoom that far? Try renting some heavy telephoto zooms for superior quality images. The sony is a cheaper option for further reach but the image quality won't be the same as the DSLR. Sensor size matters

I expect the Nikon D90 to win out

Why? Bigger sensor, bigger pixels, more dynamic range and so on!

Yet really in a way it is a questionable question. If you already go a DSLR see if you can't hunt down an acceptable size/weight 400mm. D90 being not full frame will already auto crop, not really crop but you know only take light from the middle point of the glass anyway.

400mm x 1.6 = 640mm close enough. And retaining the lovely image quality of the DSLR sensor. Remember lens quality matters though. A at most decent image quality lens will limit you.

There's a reason why the great lenses are so big and heavy, they requires more glass of better quality. And if you really want that super result. You are going to have to go for a super lens. Buying the cheapest 70-300mm will get you just that acceptable quality but not great.

Superzooms are fun but have small sensors, this means that if the light goes down the ISO ramps up. Causing less clean images! Seriously if you are serious about birds you must also be serious about what stuff you own and take with you. Even with the very good sensors of today. You can't beat size and quality of the glass in a good lens.

I would even say that the cheapest lightest zoom on a D90 will make worse pictures then a superzoom with decent glass.

Remember this well glass is the key!

The D90.