Long-term kernel choice

I’m working on a project that’s due for completion in the next 3-6 months on the BBB with multiple instances will stay in the field for approx. 3 years. We will have low-speed access to the devices, 1G GSM at best, but probably not enough to entertain onsite kernel updates during that time.
I am especially interested in solid wifi, USB and SPI implementations.
What say you, BB community - what current or soon-to-be current longterm kernel version would you take to your desert island?