[thxbb12]

another consideration is the Olympus OM-De-M1

which lens to get?

 

If you decide to go the MFT route, I'd go for the following:

• Body: Olympus OMD E-M10: great value considering its specs (and very compact).
  
• UWA: Olympus 9-18 f4-5.6: very tiny while great focal range; slow but it shouldn't matter for landscapes anyway
  
• Portrait: Olympus 45 f1.8: great value and excellent IQ wide-open
  
• Walk-about: Olympus 17 f1.8
  

Alternatively, if 24mm (FF equivalent) is wide enough and you don't need much speed, you could hit 2 birds with 1 stone: the Panasonic 12-32 lens is extremely small while providing good IQ. The range is very convenient too: 24-64 equiv.  Throw in an Olympus 40-150 or Panasonic 45-150 and you're covered from 24 to 300mm (equiv) with a portrait lens, all in a crazy small and light package:

• Olympus OMD E-M10 (396 grams)
  
• Panasonic 12-35 f3.5-5.6 (70 grams)
  
• Olympus 45 f1.8 (116 grams)
  
• Olympus 40-150 f4-5.6 (190 grams)
  
• Total weight: 772 grams, 130 grams lighter than your Nikkor 24-70