Collecting miles on TK or UA
Hi,
Traveling on Turkish Airlines for the first time and don't have any miles on TK or UA. Is it better to collect miles on TK or UA? TK miles expire in 36 months and not sure if I am going to fly them again during that period vs UA miles don't expire. Flying in J class and TK will give ~25k miles vs ~18k miles on UA for the trip. Would like to accrue where I can actually use the miles to travel within the US.
Am leaning towards UA simply because the miles dont expire but it is considerably less than the number of miles on TK. Thoughts?
Thanks.