Why are you worried about cleaning the inside of your airlines, no matter what the material is that you've used? As stated, the filters that you should be using will take care of that if correctly sized, placed/installed and of the type needed.
Copper, VERY easy to install. Once you get the hang of torching your fittings, it's a breeze. Looks nice too.
Iron/Steel pipe, heavier, may require a threading die to make threads on the end of a needed length of pipe, but it's durable and still industrial tried and true, my fav after all these years. I've taken apart 30 year old galvanized air lines that still looked really good inside.
PVC, don't go there. Hit some with a hammer to see what happens.
PEX and other flex lines, getting more popular all the time with the right material that's rated for the pressure of the system that will be used. Single stage compressors usually run at 125-135psi max, so it's a safer fit if a max limit of 150psi is a concern. Two stage compressors with their higher output may have some cause for concern or fact checking.
The concern about water and rubber or other flex lines is something I've seen too when a metal line would have performed better at cooling the air and allowing moisture to drop out easier. That's why it's not recommended to just run a flex line/rubber hose straight off your compressor if you can help it, since water vapor is going straight out of the tank and into the air tool being used since it never had time to cool/condense and be trapped in a filter .
So, I vote for using metal as your first choice, or PEX as your second, but allow for or add a water trap before your end run air filter unit to help reduce water vapor removal load on the filter at the end of your run.
Oil loss into the piping isn't usually a real issue unless your pump rings are worn or not that tight to being with. If you're spraying finishes and are really worried about oil contaim., get a second hose to use ONLY with the spray gun, and add a nice oil removing filter[coalescing? I think] that you pipe into the system as a second tier or split next to the regular filter and regulator. This way you only use it as needed, and don't add any possible oil cleaning load to it unless you're hooked up for spraying.
Anyway, that's how I'd do it.