For mortgage approval, it depends on a few things like the loan program and your credit score.
For example: On a conventional loan with less than 20% down, you'll be capped at a 45% back end debt ratio but with an FHA mortgage with 3.5% down your back end ratio can be as high as 55% as long as your file gets approved through an automated underwriting system.
If you're thinking about this from the perspective of what's best for it's going to depend on your budget and what you're comfortable paying each month. You don't want to end up house rich but cash poor.
Please feel free to contact me for more information or help. You can also find info on my FHA Mortgage website by clicking the link below.
Senior Mortgage Banker
Peoples Bank & Trust