Of those two names, I would prefer Kunkel because it's more consistent with German spelling, but it's possible that the LNAB was some other variant spelling, such as Kunckel (which appears on one of these profiles as an alternative spelling).
I've sometimes searched the web and German genealogy websites to see what spelling(s) are found currently or historically in the part of Germany the person is supposed to be from. https://www.wikitree.com/wiki/Kunkle-337
mentions a birthplace in Germany. Have you looked at familysearch (which is free) or other sources to see if you can find a baptism record -- or other records for families with this name?
If you decide that the spelling should be something like Kunckel, you should ask one of the profile managers to change the LNAB on their profile to fit that spelling before you complete the merge of the two profiles, then merge into the profile with the new spelling. (That slightly reduces the number of redirects that might be created by the merges.)
And do record all variant spellings on the profile. For example, I see that the immigration ship's passenger list called him Kunk -- variant spellings like that one that aren't either LNAB or Current Last Name should go in "Other Last Names".