I solo queue quite a bit, and tried some different ADC. The conclusion is that ones with built in escapes like ez, corki, vayne, cait are far more viable in PUG games than ones that don't have that escape. There are just so many gap closers that get a lot of play time in blind pick that its hard to play ashe and be successful. Also, playing ADC is really team dependant. You really need your team to protect you which is hard to coordinate with randos. However, in arranged team it could totally work if you had a teammates to peel for them like cho, singed, malph, lee, jayce ect.
tl;dr adc with escapes viable in solo queue, all viable in arranged team