Start behind the LE.

The fastest start is still for the Hive (or if the Hive player goes second).

I wonder, can the Hive clear 20 Imps without losses in the first two weeks, or 25 Demons?

Added 18 hours 10 minutes ago

2. Regarding Mages/Druids, I said it before - if they are guarding, I personally (I'm not a guru of this game, so I won't claim anything for others) won't attack them until I have Battle of the Elements.

1. Okay, you got Battle of the Elements, how will you deal with Druids? I don't see any way to defeat Druids without significant losses, even with Battle of the Elements, using Wing or Ossir. I just don't get it, I'm stupid. :) Will you explain?
2. There is a unique tactic for Dire, against any Mages and Archers, that is not available to other factions. The minimum level to get it is 7. You need to take Defense and Battle of the Elements, as well as Fire Elementals. Then, buy almost any random hero, take their troops, and split them into 7 stacks of 2 units each. While the Mages or Archers are shooting at them, the Fire Elementals and the hero will destroy them. The mana cost is only for the Elementals, the losses of the forest units are 0, and the gold cost for the random hero is offset by the fact that the Archers or Mages are guarding. Besides, the random hero's units may be enough for several such battles.
In general, from the point of view of clearing neutrals, all Dire needs is Fire Warriors, Battle of the Elements, and Magic Attraction. Theoretically, everything can be gathered by level 9. With these skills, you can defeat everyone, sacrificing random hero units if necessary. For example, if Druids are guarding at least one pile of gold and one chest, we can confidently attack them with the random hero's troops, and we will have already recouped everything.
3. There is a more accessible version of this tactic against weak Archers. For it, you only need the random hero's troops and Fire Elementals (you can get them at level 3): just defend with the random troops, and the Elementals and the hero will kill them.
Thus, Dire can defeat Archers from level 3. And further on, her abilities to clear neutrals only grow. Next, you need to take either Defense with Dodge or Learning with Magic Attraction. The probability of getting one of these skills is 20%! If they are not given immediately, you can confidently pump up Summoning to Expert - the number of Elementals increases by a factor of 2 compared to Strong. Or take Logistics, and the chance that you will get Logistics, Learning, or Defense is 35%. No luck is needed here. Dire will easily get the necessary skills for a rush.

If you're lucky and Ilfina is in the tavern, you can take her too - yesterday, just for fun, I checked, my wife, who may play 15 times with one Unicorn and gray-skinned Imps, easily cleared almost all of her territory (except, again, all sorts of Mages) in the first week on a random map, patch 3.1 with strong creatures, which proves the possibility of a good start with other heroes besides Dire.

Well, that's if you're lucky. But what if you're not? What if Dire is lucky? Dire with a horse and the Hive will be a terrible rusher.
I have no doubt that Wing can have a normal start on Veteran. But no more than normal. But with Dire, the start will be fast in any case, with any heroes in the tavern.

Besides, there is another factor in favor of Dire's speed - this is Learning, it greatly enhances the hero. But for Wing or Ossir, Learning will be completely irrelevant. Thanks to Learning, Dire not only develops faster in the first two weeks, but also maintains a speed advantage in the future. In addition, the faction has a high probability of getting Learning and Logistics. So, after quickly raising the hero's level, Logistics is quickly raised.

P.S. Development speed decides everything!