OK, so you want 5v, that is easy...
BUT! you want 5v at the lowest possible track voltage...
So what is the dropout voltage on each suggestion?
(what is the minimum input voltage to supply 5v output)
I think you will find a boost regulator will be superior... and the specifications on these boards will tell, but I see they do not tell you!
A normal series regulator will lose about 2-3 volts... so to get 5 volts out, you need 7-8 volts input..
If you get a boost regulator (and maybe one of these is), you could get 5 volts out from like 2 or 3 in, i.e. much better final result.
Greg