Short answer: Joint = more borrowing power but both fully liable. Get property sharing agreement. Consider pre-nup for property.
A joint mortgage uses both incomes, so you can borrow more. But both are fully responsible for the whole debt. If one person stops paying, the other must cover everything. If you split up, you are both still on the hook until the house sells or one buys the other out. Get a property sharing agreement.
Partner A Income: $50,000
Partner B Income: $45,000
Combined Income: $95,000
Single Borrowing: ~$280,000
Joint Borrowing: ~$570,000
Trade Off: More money but shared liability