300s hands down imho.

Out of curiosity, on what do you base that opinion?

I'd make sure you're comfortable with the size and weight of any lens you choose (especially with something like that Sigma). You may want to give more details on what type of wildlife for better responses, too.

As for a macro lens, the same thing applies. I'd give some details on what you want to take photos of. For many closeups, you may not even need a dedicated macro lens. Taking a photo of a flower bloom is one thing, taking a photo of a tiny insect is something else (requiring a lens able to fill the frame with a smaller subject).

If you really need a 1:1 Macro lens, the Sigma lenses are popular (Sigma 105mm f/2.8 EX DG Macro, Sigma 150mm f/2.8 EX DG Macro and more). Ditto for the Tamron 90mm Macro. These are 1:1 Macro lenses (able to "fill the frame" with a subject the same size as the camera's sensor at their closest focus distance). Many zoom lenses are 1:4 already (able to fill the frame with a subject that's 4 times the size of the camera's sensor or film). Some zoom lenses are 1:2 at their longest focal length. So, for many subjects, you may be able to get by with a typical kit lens instead of a dedicated 1:1 Macro lens. It all depends on what you're taking photos of.

Working distance also comes into consideration. For example, you may be able to fill the frame with a smaller subject using a 50mm or 90mm 1:1 macro lens. But, depending on the subject type and lighting, you may be better off using a longer focal length lens and shooting from further away (so that you're not blocking light and casting shadows, spooking smaller subjects, etc.).

Just my 2c...
I wish the Canon has the features of the Nikon which will make the 7D perfecto!!!

1. There's much more AF points on the D300s for a subject to lock on, and more ways to configure the AF points around the center AF (similar to a 1D series than a 7D)
-> This will help a lot on smaller subjects (i.e. small bird) which transition between AF sensors unlike a big football player which may cover multiple AF sensors

2. I use all three brands (Canon, Nikon and Sony) and the Nikon auto ISO is probably the best feature which must be emulated on all cameras
-> One just select the shutter AND aperture needed for the desired effect and the camera ISO will slide to match (this ISO range can be bound)

3. Direct GPS support from the camera
-> Geotagging on a Canon is quite cumbersome and expensive

About the only downside to the Nikon are its Tele lenses (unless you stick with 3rd party)
-> Be prepared to pay a big premium for them over the Canon's, that is if you are fortunate enough to find them in stock...

I would also like to know any particular reason.I would be glad if you let me know.

Thanx NHL for your inputs but cost factor I think canon leads as what I am getting to know from these threads. Specs on nikon are less as compared to Canon

Hi Jim,

We for wild life photography I would be on jeep and capturing tigers/Elephants/Deers and wild animals.capturing these animals would be from far away place such as jeep. and about Macro photography would involved with Food,Tabletop models ,scale cars etc. I think I would be opting out for Canon cause feature wise it is rich. Can you clear my doubts on what does APC or APS sensor stands for ?

Abhi.

Thanx Jim for your valuable suggestion I finally decided to go on Canon 7D with 50mm 1.8 Prime lens and 10-22 Wide angle lens. I have opted for Wildlife photography using 150-500mm Sigma lens. and for general photography using Canon 18-200mm lens.

Regards,
Abhi.

Canon is the best camera for me.. I used canon for almost seven years already and I love the result.