Lens advice for a Nikon newcomer

I'm jumping ship from Sony and planning my new lens lineup with Sony, and just wanted some advice. I'm not a full time paid photographer, but I use to have some payed asignments. My most common camera use is in the studio, with flashes or continual light, but also do other kinds of photography: nature, low-light, theater plays... I'm looking the best bang for the buck solution, because I cannot spend that much...

This was the equipement I had with Sony:

• Sony A700 (12Mpx APS-C)
• Sigma 10-20 f/4-5.6
• Minolta 28-75 f/2.8
• Minolta 50 f/1.7
• Tamron 90 f/2.8 macro
• Sigma 70-300 f/4-5.6 APO DG Macro
• Metz 58 AF1 flash

• Nikon D600 (24Mpx FX)
• Sigma 12-24 f/4-5.6: ultra wide angle for nature, landscape and travelling
• Tamron 28-75 f/2.8: normal lens for studio use
• Tamron 70-300 f/4-5.6 VC USD: nature and wildlife