My go to is a Nikon d600. I'm transitioning from portrait work to more nature/wildlife.
Just picked up a used Tamron 150-600.
Looking to get a 2x converter for my Tamron 70-200 2.8 for lower light days.

Also, I just picked up a camera harness for hiking so I don't have to hand-carry the equipment between spots or stuff things back in my backpack. Looking for recommendations from folks on how they hike with heavier equipment.

I also have a Fujifilm xt2.
Fujinon XF 70-300 is my favorite telephoto.
XF 10-24 f4.

I pick up used lenses as they make sense for either system. Depending on the lighting for the day I'll grab either camera.

Nikon D7100, D7000 and D750

Tamron 28-300 3.5-5.6
Sigma 150-600mm 6.3
Quantaray (Tamron) 70-300 4.0-5.6
Tamron 200-400

Canon R7 and 250D

RF 100-400 5.6-8
RF-s 18-150 3.5-6.3
EF-s 18-135 3.5-5.6
Sigma EF 70-300 APO DG 4-5.6

‎M:
Currently using a Canon R6 mostly with an EF100-400L Mk2.

Hi everyone, I currently use a Sony A7iii with a Tamron E 150-500mm F5-6.7 lens for my bird photos, very happy with the results :-)

Nikon D700, D3, D300, D800, Z7 & F3, FG. All are resting comfortably in my equipment closet except for the D700 and D3 which have amazing sensors.

Canon 90D and 5D Mk ll
Canon EF 17-40L, 24-105L, and 70-300L, all but the 90D bought used at great value!

‎M: I have a Nikon D850 and a 200-500mm Zoom. Sometimes I shoot with my older D7100 and I have an 18-300mm lens

I use the Nikon Z50 with the new Nikkor 28-400 lens. I'm actually very happy with it.

I use a Sony A1 with 100400GM lens.
Happy with it for many years.

I use a Canon R5 with RF 200-800mm f6.3-f9. I love this combo.

Sony A7RV
Tamron 150-500mm f/5-6.7 Di III VC VXD

Since posting 8 months ago I have sold the A6700 & A7R3 and now have a Sony A7Cr which I use with my Sigma 160-600 Sports. The high resolution allows me to crop in a long way, and the autofocus is brilliant. Sticking with what I have now.

I've decided to niche into something "retro" and use gear that isn't common! Currently using:
Samsung NX500 w/ 16-50mm kit, 16mm prime, and 50-200mm telephoto.
Also use a Kodak Retina iiic 35mm rangefinder camera!

Nikon Z8 with Ftz and a F-Mount Sigma 150-600mm f/5-6.3 Contemporary

Recently upgraded to the OM Systems OM1 MKII and purchased the OM System M.Zuiko Digital ED 100-400mm F5.0-6.3 IS II with the 1.4 Teleconverter. The lens is replacing my Leica 100-400 f4-6-3. I had great results with the Leica lens but expect better with the OM Systems lens due to Sync IS and being able to use the teleconverter.