I’d say for those who have the option and plan on doing the full 20 years, stay with the traditional to get the 50% pension. If you plan to get out before 20, I’d take the new system for the 5% government match in the TSP.
It depends on if you plan to do 20, how long you have in, and how well disciplined your investing is.
The short answer: It depends. For the overwhelming majority of people, the BRS is a better deal. Something like 87% of servicemembers do not make it to 20 years. Some money > no money.