Understanding Battery discharge rating
That table tells you two things.

1) The slower you discharge the battery, the more capacity you'll get. Compare the 20 hour figures, which give more or less the rated 100Ah capacity of the battery, and the 60 minute figures of around 60Ah.

2) The deeper you discharge the battery, the more capacity you'll get. Compare the 1.8v and 1.6v endpoint voltage figures on any column.

Now you get to choose what endpoint voltage you want to use in your application.

The deeper you discharge the battery, the fewer charge/discharge cycles it will deliver before wearing out. Do you want high capacity, or do you want a battery that lasts many charge/discharge cycles? You can't have both. 

If you're lucky, the battery data sheet will have a graph or table of expected number of cycles versus endpoint voltage. 

A battery like this is quite well suited to an application where you habitually use only 50% of the rated battery capacity, but occasionally need an emergency reserve that is not used all that often. You sacrifice a little bit of battery lifetime for high capacity when you must have it.