I like substantial feeling cameras, and up to a point the weight doesn't really bother me.
For reference, my main DSLR is a Nikon D5, and if I need a second body depending on the exact situation often will use another single digit body(D4 or D3x) or a D850. I always have a 24-70 f/2.8 on one of these. With that said, one of the things that really thrilled me about the 70-200 f/2.8E FL I picked up last summer was how much lighter it was than my old 70-200 f/2.8G VR.
On 35mm or 35mm format digital, there's a point where I say "enough" on weight, and for me I find I start getting a little shaky hand-holding my 300mm f/2.8(G, VR1) for more than a few minutes. Maybe I'm a wimp as I know people hand hold these lenses all day, but it's in monopod territory for me to use for very long. That's especially true on a heavy camera like an F5 or a single digit D.
In medium format, funny enough my Pentax 67 has never bothered me to carry for very long. My 555ELD with a 350mm Tele-Tessar gets a little to front-heavy for me to carry for very long.
I get really uncomfortable using any camera without a strap. About a year and a half ago, someone clued me in to the Peak Design system, and it's everything I could want in a strap. I have neck straps from them in 3 different sizes-the "Slide", which is 1.8" wide, the "Slide Lite", which is 1.3", and "Leash", which is 3/4". All are heavy nylon webbing-think seat belts but softer/smoother. The Slide and Slide Light have some padding with some minimal but surprisingly effective "grippies" in the center, while the leash is much thinner. All of them are fairly breathable, something that I feel like is lacking in heavily padded straps like Opt-tech. Peak anchors are inexpensive, secure, and fast to attach-detach to the straps. plus are not particularly invasive when they're there. That means that even though the straps themselves are expensive, it's so easy to switch them between cameras that a few straps cover me for everything. I find the Slide Lite or Leash ideal for a lot of 35mm cameras, while the Slide Lite or regular Slide are more at home on medium format.