For a start, buy a brand name, like Hansen Couplers or Goodyear air hose. Brass or steel fittings are normally pretty good, but stainless steel is always an option. There are many different coupler configurations and sizes as well, so if you need to replace the whole pile, maybe it's time to dig into the catalogs to be sure that you have the right sizes and styles. The universal 1/4" industrial interchange we all use is limited enough that any air load over about 6 CFM should probably be on a larger air hose and a larger coupler size. I have several impact wrenches, and one of my wrenches will do virtually nothing unless it is on a 1/2" air hose with 3/8" connectors. Years ago, I had one wrench that needed at least a 3/4" air hose - it was a 1" drive, and I never found a bolt that it couldn't remove. Air tools are designed for 90 PSI at the tool when it's running. Make up a T fitting with a male & female connector and a gauge. Connect it right at the tool's inlet, and see how much pressure drop your hoses and couplers cause.
Nothing lasts forever - I just overhauled part of my air system, and 90% of the leaks are now gone. I found that I had some 20 year old quick connectors that were worn out, and they weren't sealing very well anymore. After replacing them, my system will now hold pressure overnight.
You used to be able to buy rebuild kits for some of the couplers, but I haven't seen any for years. Every old coupler I've opened up for failure analysis didn't have much left to rebuild anyway, so replacement becomes a better option.
Scruffy is right - a tool that vibrates needs a short hose whip that screws into the tool.
I also just installed bleeder-type air valves in my primary locations. When you disconnect an air line, the pressure blast can cause problems, but a bleeder valve releases the pressure through a fairly small orifice. The end result is a quieter disconnection, no hose whipping, and reconnection is a lot easier with a -0- pressure air line. Once connected, open the valve.