What will you be using the knife for? My advice is to do a little research on the types of steel and their performance as well as the customer service of each company.
I have both knifes and I've used them, a LOT. You can't go wrong with either of these. The Becker is a fantastic value and mine have always held an edge very well- but there really isn't much comparison as far as toughness, (especially if your talking about a 5160 Ranger- great steel for a big blade). Actually I can't imagine breaking either one and I own a dozen or so Beckers. I just don't chop concrete, ever. If I needed to I'd buy a big crowbar.
I started out with The Becker Brute, the BK-9, RD9, worked my way up to a Battle Mistress, and ever since I've been working my way back DOWN the scale. It's been a while since I've carried anything bigger than a 5 inch blade.
I haven't had any experience with Ontario since they started making the RD9, but Becker's customer service has usually been pretty good. You tend to get what you pay for, and there is a noticible difference in quality that fits the price point on both the knives you mentioned.
Another company I'd put in there next to Ranger is Rat Cutlery. Great, hard working knives and the service is second to none, outstanding value overall- I'm just not sure if Rat makes anything with a 9 inch blade?
I've always thought of Ranger as occupying the middle ground between Becker and Busse, both in terms of toughness and fit and finish.
Good luck!