Hilton. Also easy to get elite status if you want it. Get the no annual fee Amex Hilton HHonors card and you automatically get silver status. Spend 20k annually on the card and you'll get gold status.

Hilton does have good international exposure but I've been recently using them for less dense areas in the US where you'd be hard pressed to find a nearby SPG property. For example my last two stays were at Hilton Hampton Inns, one in Sandusky, OH to visit Cedar Point and another at Youngstown, OH where SPG locations are nowhere to be found.

Another upcoming stay for a skydiving event also happens to be at a Hampton Inn. SPG is great for urban cities but they don't have a brand under their umbrella that's as widespread and equivalent to Hilton's Hampton Inn.