Quoting Glazunov1, reply 39
While Warlock doesn't have a tactical map, using 1upHex makes the entire world a tactical battefield and, unlike FE, that battlefield uses terrain modifiers or specializations on them. In FE we only battle upon a flat field with some obstacle tiles, otherwise there isn't much to it. In this respect Warlock manages to have more depth than FE.
Warlock has terrain modifiers, but FE has obstacle tiles, multiple units, dodging, and movement over a (relatively) large field of battle. I'd give this one to FE. Though I'm a fan of hex-based strategic battle games.
Warlock also has some more depth in the selection of how spells are cast as you can only use so many spells within a turn. In FE you are only limited to mana.
I'm not sure I understand how this is a factor of gameplay depth. It is a different way of limiting spells, but Warlock's method is no better nor worse than FE's. FE, on the other hand, adds a lot more spells with much greater diversity of spell effect. And different sides, empire or kingdom, are also limited in terms of certain spellbooks. Warlock doesn't have these.
Additionally, while Warlock doesn't have unit design, it does allow us to customize units as they level up. In FE only champions gain this benefit while units gain their unique traits at the start and cannot adapt as they grow (at least I haven't seen anything except hp boosts from troop level up).
FE allows customization of units at the start. Warlock doesn't permit this, but provides buildings from which you can purchase armor, etc, for specific units. Arguably FE has something like it in buildings that add levels of skill to new units. -But I see your point, here. Warlock leverages new buildings to affect units you've already got. It's something FE doesn't have at this time, and may not have, in its final release. But I think we're overlooking my main point...
FE does promise more depth overall but it doesn't run away with its victory at this point.
I'd have to disagree with this assessment. Although we can argue the implementation of a few specifics, there are many more gameplay elements already present within FE. That's not opinion. It's simply fact. They're certainly far from finalized--this is still mid-beta--but the statement, "Ok, no problem, I certainly hope FE will be deeper than Warlock," ignores that FE is already has the far more ambitious game design, and the one that takes most of its elements further along than Warlock--when Warlock has similar ones.