OM-D E-5 III - $1200, 414g
Olympus 12-40mm 2.8 - $1000, 382g
Sony A6600 - $1200, 505g (has the meme real time tracking gets more shots in focus)
Zeiss 16-70mm 4 - $1000, 307g
35/2.8 = 12.5mm aperture vs 50/4 = 12.5mm aperture, 2.8 and 4 are equivalent here and the sony has superior reach and AF
Same price, 6 grams difference, better reach, better qualiy. Better all round options for other things.
If you dont care about IBIS, then A6400, same amazing real time tracking, 403g instead of 505g, so actually its lighter than the MFT setup, and $900, so also cheaper too.
Fuji XT3 + 16-80mm 4 kit $2000
539g + 440g
weighs a little more but costs less, not sure how good the lens is more AF vs OM-D, but cheaper, more reach.
Lenses for the FF are the same or a bit cheaper
Tamron 28-75mm 2.8 $880, 550g
Heavier, but cheaper, but its a not a 2.8 MFT equivalent, its a 14-38 1.4 equivalent which doesnt exist for MFT.
Zeiss 24-70mm f4, $800, 426g
Similar weight, cheaper, and actually 12-35mm 2.0 equivalent, not 2.8
The body will cost more, eg
A7iii around $2000, and body is heavier at 650g, but this will feel better balance, the center of gravity will be closer towards the body, also its not that heavy with one of the afore mentioned lenses.
How about the Olympus 45mm 1.2? An 85mm equivalent is something one might get with a 24-70mm equivalent
Olympus 45mm 1.2, $1300, 410g
Panasonic 42.5mm 1.2, $1600, 425g
(2.4 equivalents remember)
Sony 85mm 1.8, $600, 371g
MFT is a fucking meme, and while the body may be cheaper than FF, you could end up the same price, or cheaper, same weight on a FF setup with superior AF, and IQ.