I played it one time against AI and watch several games. Here is my review.
I think the changes at the center now favors Ranger over Horse Lord. There are more flyers so anti-air becomes handy. You don't need high Undead Lore, so there is nothing a Ranger or Assassin-Ghost combo can't handle. The items are better now so getting the ruins might have more return.
With very strong starting units (sandworm,gryphon,elements) I would take a Ranger now instead of a Horse Lord. Ranger gives speed and open ruins meanwhile.
With starting units given stack bonus (battering ram, catapult, medusa, yeti) I would take a Barbarian and forget the ruins until the next hero comes.
With very bad starting units (bunch of light infantry) I have to start with a Valkyrie and hope to survive the first few cities.
I think Assassin might be one of the worst starting hero in this map unless you are starting with a Ghost or a Wizard. It gives very little as stack bonus initially. Also very risky at ruins. I hate to train scouts for ruins at my capital for UL, I rather train Light Cavalry, Wolf Rider, or even better troops. I like Assassins when they come with a medusa-ghost or as level 2 hero.