Plan fees for my TSP are .027. I think I'd have a hard time beating that anyplace. The downside is very limited withdrawal options. When I retire later this year, my options are: a full or partial lump sum withdrawal, rollover of full or partial balance into an IRA etc, or monthly equal withdrawals that can be adjusted just once each year.
If I decide I want to buy a new boat, or need an extra $10,000 for an emergency, I cannot withdraw it from my TSP. The limitations are part of the reason the fees are so low. I like the low fees, and the somewhat limited investment options in the plan are adequate for my purposes.
Also, I like the relative safety of the G fund, which is only available in the TSP. I don't plan to keep my money there (G fund) on a permanent basis, only when the market is in the tank long-term.
TSP withdrawals are taxed by some states, but not others. In Texas, where I currently work and have a legal residence established, it would not be taxed by Texas. However, wife wants to us to be retired in Louisiana (where she is living and waiting for me to retire and get rid of my "bachelor pad" in Texas). That would mean my TSP would be subject to Louisiana state income taxes. In reality, the amount wouldn't be huge. I believe maybe 2% or so. My federal retirement and my military retirement won't be taxed in either state.