In 2009, when the Panasonic GF1 came out, I was ripe for the picking. I'd been using the great LX-3 and the GF1 seemed the natural progression.
But time and sensors moved on and it didn't seem that there was going to be a worthy Panasonic successor to the GF1. Of course the PENs were great, but I wanted an in-body EVF.
I was sorely tempted by the Fujifilm X100. If Fuji had brought it out with a 50mm (equivalent) lens, they'd of had me.
But then came the NEX-7. I didn't like the look of it when I first saw it. But after the extended production delay (floods—not their fault), when I was finally able to handle one, it was incredible. The tri-navi controls were outstanding. It had the best EVF I'd seen. And it had a ground-breaking sensor. The lens selection was limited, but I'm not a long-lens shooter, so there were enough.
There was a difference in sensor size between the NEX and M4/3, but it wasn't the slight size difference that attracted me to NEX. Quite the contrary, it seems to me that above APS-C, the attendant lenses, particularly fast and stabilised lenses, pick up size and weight at an alarming rate.
It's fashionable, at this point to say something like, "I've never looked back." But that wouldn't be quite true.
I watched the Fuji X-Pro1. I was very impressed by its optical/electronic viewfinder, classic controls, and the initial, high-quality lens line-up: 18, 35 and 60mm. And, the X-Trans sensor array seemed to provide a neat trick for avoiding moire; but I was scared off when Adobe couldn't seem to come to grips with effectively de-mosaicing the RAW files.
Since then I've looked back at M4/3 a couple of times. I'm glad that Panasonic moved forward in 2013 with the GX7, but I still prefer my NEX-7 from 2011.
Of course the OMDs fluttered their eyelashes in my direction. Stabilisation, weatherproofing, size, sensor — what a combination. And there was also the nostalgia factor, as my last SLR was the OM2-S. But the OMDs just didn't have the right feel for me — perhaps because I'd owned an OM2-S.
The Zeiss Touits and Sigma offerings have since filled the Sony E-Mount gaps, except for an 85mm.
Nothing's perfect; but if this isn't a "Golden Age" of photographic tools, I don't know what is.