Bitcoin used to be better, but right now it's not really.
It's quite sad but the fees are getting higher and the transactions are getting slower, so might as well use WU.
Yes right now the fees of bitcoin transactions are getting higher and time is taking longer which is disappointing for the users but still it has less fees in compare to WU and even bitcoin transactions are available 24/7 which is not possible with WU.
The 24/7 availability is not there with Western Union, but as we are not in need of an intermediary service provider we can make bitcoin transaction anytime. Recent days few was found high but this is just a temporary problem which will be solved once technology retains from the ongoing digital war.
I was using WU when I was not aware about bitcoins but after discovering bitcoin I have stopped using WU as I think that the fees of bitcoins are too lower in compare to WU and I am sure when many people will be aware about bitcoins they will follow the same.