It depends on the cost of living adjustment. A full cost of living adjustment is very expensive to purchase in the private sector. A limited adjustment such as limited to 3% reduces the periodic annuity payments by a modest amount. I am not sure about the cost of living adjustments in the Texas plan. The website is not clear about the benefits.
At my company, 95% of the employees take a lump sum value retirement amount rather than a fixed annuity.
A fixed monthly sum forever sounds great until you have a Jimmy Carter come along and turn it into peanuts.