It depends a lot on your origin and destination. In my 6 years, I’ve found the optimal corridor to be Downtown Brooklyn to Midtown, with a slight bias for west manhattan over east. Anything outside that corridor has a high potential to be the Wild West (the G, L, JZM, etc) with kafkaesque reroutes and delays and express running local and no trains after 9pm on random 5 days every 9 weeks.