I recently received a Sony 24-104 f4 lens and I love it. This lens is so versatile. I can see this as my main travel lens. On most trips I will still take the Sony 16-35 f2.8 GM for landscapes. Smaller international airlines have a 8KG carry on luggage limit. That means a maximum of three lenses so selection is very important.
Don't just take my word for it. The reviews for this lens are really outstanding. Some are even saying go with this lens over the 24-70 f2.8 GM. Much cheaper and lighter.
A question haunting me: The Sony A7 Mk II offers 24mb resolution. I shoots birds and butterflies; even with a 400mm lens, very often I end up cropping the FF image to APS-C size or smaller; often I shoot in APS-C mode for 'perceived reach' that gets me a 10mb image file. How would that compare with using say the APS-C size Canon 80D (also 24mb)? Here I would have a non cropped 24mb file as compared with a similar Sony A7 cropped image which would be a 10mb file. Which would offer better image quality for making prints of size 20x30 inches?
Around noon in an iconic Icelandic spot. Early December of 2016.
Sony A7 with Olympus OM 18mm manual focus lens. More images made with this lens and the A7 here: http://fourbillionyears.org/a-tiny-giant-om-zuiko-18mm-f3-5/