Welcome back! I myself had quite a few interesting years with a Fuji kit, although I never let go of the Nikon gear I had at the time. Man, that X-Pro 1, then X-Pro 2, were beasts! I wish Nikon would make a gorgeous and innovative camera like that. And the lenses were remarkable, too. I ended up reselling the whole lot as I became too frustrated with the lack of performance of the small sensor (versus Nikon’s), especially in terms of dynamic range and color fidelity.
As for long lenses, I am perfectly happy with my Nikkor Z 100-400, but I don’t do wildlife these days and I know the reach might not be long enough for birding. Still, I only have S lenses in the Z-mount, and I wouldn’t stray away from those. But that’s probably just me.
I was on the fence for a mirrorless for video and most importantly - USB charging, and in 2018, Nikon fell flat on their face NOT offering the charging on the first gen of Z bodies. Fresh X-T3 had just that. Prior to that, I had and have Xpro1 with 27mm and 18mm/2, so I was generally familiar with that ecosystem. So when Z6 and Z5 were priced right around a T3 - T3 was an absolute winner in terms of features.
Another thing at the time was wanting a birding setup, and APSC made more sense, plus Fuji having 100-400 kinda sealed that deal.
Had to get redundant glass, sure, but it all ROI'ed quickly and wasn't an issue. I too kept all my F bodies and glass knowing that they're all solid/backups/etc for when I might need FF sensors.
Then I got a cheap GFX50R, and that made F gear, as well as lil Fujis totally obsolete for the fun factor and IQ.
And now we're here: "refurb" Zf with 115 on the shutter for $1200 straight from Nikon, FTZ to use all my old glass and then some, and as of today - the 26mm I've been praying Nikon to make for over a decade.
Little Fuji gear but the Pro1 and 18/2 are going up FS this week without a second thought.
