well for TAC I think publishing order is definitely better cuz if you didn't you'd knew Tobias's lineage way too early, it'd be no fun.
Also the point of that is to show what Elfangor was. For 13 books he's this legendary hero, champion of our little team of heroes, then TAC comes in and says "no see, he messed up too, he wasn't a war god, he bad mistakes, learned and got lucky, just like these guys are doing."
Which is why TAC is after 13 on my next reread-normally I do it first.
I don't know where to but TEC, I think the publishing in order would be better, just cuz it really throws off the "this is the very end" feel of the series, plus it kinda seems real obvious who's gonna go first if it's done b/w 53 & 54. Even though I already know