Official: Sony FE 70-200mm f/4 G OSS II Lens
The Sony 70-200 G f/4 II looks like another very good lens option, although I will happily stick with my Tamron 70-180.
Sony 70-200 GM f/2.8 II: Excellent image quality, OSS, f/2.8, relatively light for what it is although the heaviest of this group, takes teleconverters. On the downsides, relatively low maximum magnification (although not unusual for its class), expensive.
Sony 70-200 G f/4 II: Gives up a stop of aperture. Still has OSS and takes teleconverters. Cheaper than the GM f/2.8 II but still fairly expensive. Is more compact than the GM f/2.8 II, relatively light for what it is (although not as much lighter than the GM f/2.8 II as I, and I think many others, were anticipating), and has relatively high maximum magnification.
Tamron 70-180 f/2.8: Gives up 20mm at the long end, OSS and the ability to take teleconverters. Not as good for tracking fast moving action as the GM and the G(?) (My Tamron has been fine for tracking moving subjects but equally I haven't yet used it to try to photograph fast, erratically moving subjects.) However, it is f/2.8 but at a size and weight, and with a relatively high maximum magnification, similar to the G f/4 II (although the maximum magnification is not as high as the G f/4 II can get when used with a teleconverter), and is the cheapest lens of this group.
Pick your poison.
EDIT: As noted in a later post, I overlooked the fact the Tamron 70-180's maximum magnfication matches that of the G f/4 II only at 70mm and using manual focus. Otherwise, the Tamron actually has lower maximum magnification than the G and GM (atlhough I believe not much that lower than the GM f/2.8 II).
Sony 70-200 GM f/2.8 II: Excellent image quality, OSS, f/2.8, relatively light for what it is although the heaviest of this group, takes teleconverters. On the downsides, relatively low maximum magnification (although not unusual for its class), expensive.
Sony 70-200 G f/4 II: Gives up a stop of aperture. Still has OSS and takes teleconverters. Cheaper than the GM f/2.8 II but still fairly expensive. Is more compact than the GM f/2.8 II, relatively light for what it is (although not as much lighter than the GM f/2.8 II as I, and I think many others, were anticipating), and has relatively high maximum magnification.
Tamron 70-180 f/2.8: Gives up 20mm at the long end, OSS and the ability to take teleconverters. Not as good for tracking fast moving action as the GM and the G(?) (My Tamron has been fine for tracking moving subjects but equally I haven't yet used it to try to photograph fast, erratically moving subjects.) However, it is f/2.8 but at a size and weight, and with a relatively high maximum magnification, similar to the G f/4 II (although the maximum magnification is not as high as the G f/4 II can get when used with a teleconverter), and is the cheapest lens of this group.
Pick your poison.
EDIT: As noted in a later post, I overlooked the fact the Tamron 70-180's maximum magnfication matches that of the G f/4 II only at 70mm and using manual focus. Otherwise, the Tamron actually has lower maximum magnification than the G and GM (atlhough I believe not much that lower than the GM f/2.8 II).