New to this: when people say the note is the asset, what makes one note worth more than another?

I'd separate two questions that sound like one. There's what makes the note safe to hold, and there's what makes it easy to price for someone who has never met the borrower.

Seasoning does most of the work on the second one. A buyer of paper can't interview your borrower or drive past the house every month. What they can do is read a payment history, and twelve or twenty-four months of on-time payments through a bank or a licensed servicer is evidence they can actually verify. A note with three payments on it, collected by Zelle, with no servicing record, is a stranger's story about a stranger.

The documents matter more than beginners expect too. If the mortgage or deed of trust was recorded correctly, if the legal description matches, if there's a title policy naming you as lienholder, the paper is clean. If any of that is missing, the discount you get quoted is partly the cost of somebody else fixing it. Recording requirements and whether you use a mortgage or a deed of trust vary by state, so confirm your own state's practice with a closing attorney before you write anything.

Down payment matters, and I'd still put verified payment history first.

Equity. Everything else is a story about the borrower, and stories stop paying in year three.

Some vocabulary first, since the thread is using it fast. Seasoning means how long the borrower has been making payments on the note. Loan-to-value at creation is the note balance divided by the property value on day one, so a 320k note on a 400k house is 80%. A servicer is a third party you pay to collect the payments, keep the ledger, and send the tax forms.

On your actual question, note buyers price four things and they don't weight them equally in every deal. Equity position sets what they recover if the borrower stops paying. Payment history tells them whether that recovery question is likely to come up. The interest rate sets the cash flow they're buying. Document quality decides whether they can enforce the lien without a lawsuit to fix it first.

What @sextant and @warrant are describing is a real split in the market. Buyers who plan to hold the paper lean on equity. Buyers who plan to resell lean on a verifiable payment record, because that's what their own buyer will look at.

One practical note for someone at your stage. Whether owner financing on a given property triggers licensing or disclosure duties depends on your state and on how many notes you originate, so ask a real estate attorney in your state before you carry anything. That question has a different answer in different places.