Is there any way to get 4.4 on my Galaxy S4 AT&T (4.3)?
Legitimately? Wait until (if) AT&T releases a 4.4 update.
Otherwise, find a ROM written by someone who may or may not know what he's doing, flash it and hope you have a phone that's working or only soft-bricked. (And forget about any warranty or insurance you have on the phone.)
Is there any hurry? 4.4 is scheduled to be released to the GS4 in January (according to the leaks I've seen).
I have 4.4 on my Nexus 7. No need to rush, IMHO. Not much of a difference.
Separate names with a comma.