Do you usually pick the minimum connection time available or allow more time? If it varies, what are the main factors in deciding?

In this case, I was looking at flights FAT-DFW-LGA and saw choices including 45 minutes and 1:45. Originating flight is at 7am. If it's late there are many additional flights each day. Main downside would seem to be having a lower chance for an upgrade (whatever chance a PLT has from DFW midday & midweek) and not getting a good seat. Main upside is obviously avoiding an extra hour in DFW.