staying on disney property vs universal property

[Aurora]

Also, FOTL access all day long is a huge perk as is not having to take transportation to get to a park. That alone saves you at least an hour to two hours everyday if you park hop.

This is true, and if you're staying at Disney and plan to purchase a FOTL pass at Universal, that is a big additional cost per person. Plus, if you're buying the pass, you only get one FOTL privilege for each attraction that offers it, as opposed to unlimited FOTL privileges if you stay at a Univeral hotel. So yet another thing to consider.

IMHO, if you're planning to visit Universal and Disney, split stays are the most cost-effective!