In reliability analysis, MTTF is the average time that an item will function before it fails. It is the mean lifetime of the item.
With censored data, the arithmetic average of the data does not provide a good measure of the center because at least some of the failure times are unknown. The MTTF is an estimate of the theoretical center of the distribution that considers censored observations.
The Weibull and smallest extreme value distributions have similar MTTFs of around 69500 (Mean column on the table). The exponential distribution has the largest MTTF at 75858.8.
If all the distributions provide an adequate fit, you may want to select the lognormal or exponential distribution because of their slightly better MTTF.