Which telephoto lens for my Nikon?

I have recently posted a similar post.... still needing advice before I make the investment.

Right now I am deciding between the Sigma 300mm f/2.8 and the Sigma 50-500mm. The 300mm is the most I want to spend on a lens. The low f stop still gives me the room to add a teleconvertor to get that extra reach. The 50-500 is considerably cheaper. You give up several f stops for the cheaper price though.

Do I spend the extra money for the f-stop? Or save the money and get the other (nicely reviewed) 50-500mm?

Lens will be for bird/wildlife pics...

Or is there another lens out there that I may be missing out on?

Thanks-

I haven't used either lenses but my recommendation between the two would be the 300mm. A high quality 2x teleconverter should make it a good 600mm f/5.6 which is a nice length/speed for birds.

A 300mm is a nice length for shooting close ups by simply using an extension tube. And an f/2.8 would be fabulous for low light shooting. Versatile enough to use for sporting events - indoor and outdoor.

In short, a good 300mm lens is a very versatile lens.

Thanks Loup!