Based on the historical class, from the previous edition, you could make an even argument for either Con + Int or Con + Cha, because both sub-classes were represented equally.
I went with Con + Cha, in this poll, since the Inspiring aspect of the class seems more iconic than the Tactical aspect (to me).
Tough. Str, Int, and Cha all makes sense, since they were the main stats they used previously. But every 5e class has 1 major save proficiency (Dex, Con, Wis). Out of those, Con definitely makes the most sense. I'd probably go Int over Cha for the minor save, since Charisma saves tend to be more resisting effects due to your magic presence (spells like Banishment).
Makes sense, though in 5e DEX makes as much sense for a Fighter or Warlord or any other melee-weapon-user because of how neatly this ed handles finesse.Strength and Intelligence. To me a warlord is a tactician (Intelligence) that leads while in the thick of things (Strength). They're in battle calling out openings for others to take advantage of.
Makes sense, though in 5e DEX makes as much sense for a Fighter or Warlord or any other melee-weapon-user because of how neatly this ed handles finesse.
I was thinking INT & CHA, myself, but like INT & STR, it's two less-important saves, which breaks the usual pattern. STR, INT & CHA would be pretty bad, really, but would fit the Warlord's original primay & secondary stats. Another case where following 4e too closely wouldn't work out so well...
So INT and an important save - CON or WIS, most likely. Let's see, a Warlord, even if not the tactical kind, must be alert to enemy tricks (INT) and able to soldier on in times of hardship (CON). Yeah, that works.