How do I determine the lowest mac address on a 2950 switch? example 0014 16c43 653d or 0014 16c43 b501?

It's the lowest one numerically. MAC addresses are based on the hexidecimal (base 16) system which uses the digits 0 - 9 and A - F. In the example you gave the last grouping of 4 digits is unique. Since 6 is numerically lower than B, the one ending in 653d is the lowest.

Actually, you've given invalid MAC addresses there. A MAC address is 12 digits long and the ones you have provided are 13 digits. The 16c43 in the middle is invalid. And for what it's worth, those aren't Cisco MAC addresses either, they belong to Scosche Industries

As my mind boggles trying to think of any properly designed protocol that would *care* which MAC address is "lowest".. ;)