Rolling over civilian 401k to TSP vs my current Roth IRA

So I'm enlisted in the Army (active duty), shipping out this August.

I have a pretty big chunk of money in my 401k (13 years working as a civilian) and I also have a Roth IRA.

I was initially under the impression I would just roll it all over into my Roth, but I just learned about the TSP offerd by the military.

After looking into that, I am finding mixed opinions on the TSP vs Roth IRA, however, the opinions are on circumstances kinda reversed to mine, as it's mostly people getting out of the military or doing both TSP and IRA while in AD.

And suggestions for what to do with 13 years of retirement money earned and saved as a civilian, now going into the military?

Is there any benefit to having all that money from my 401k in the TSP or should I just put it all into my Roth and start a fresh TSP?

Thanks