First Line Deleted, see edit.
The LRT is the more common variety in use, and it's a good long range scope
The TMR is a very precise reticle, I like mine.
Some people want the adjustments to be the same as the reticle, meaning that if you got the TMR reticle you'd also want to get the 1/10 mil adjustments.
Realistically, that only matters if you are ranging with the reticle and/or calling shots and corrections via the reticle. It's a speed and convience thing, not absolutely necessary to have them match.
I personally prefer MOA reticle with MOA adjustments if I have the choice.
If the ER/T model is FFP, then it will be more expensive, but you wont have to use the scope on a certain power for the spacing to be as advertised.