These threads come up periodically and it always boils down to what each individual values and prefers. There is no perfect loyalty program, but certainly ones are better suited for different types of travelers.
As a reformed Hilton Diamond I've found that SPG works significantly better for me as a top tier. Quick data set:
- Hilton wins on sheer volume of properties. It's pretty hard to find a location where there's an SPG but there isn't a Hilton.
- SPG wins on consistency and quality of those properties.
- Free internet is a wash
- Consistent free breakfast is a win for Hilton
- Corporate customer service is a complete cluster f* at Hilton
- HHonors is about as easy to understand as the tax code. Not even the employees get it.
- Value of points is clearly in favor of SPG
- Hilton consistently runs better promos
- SPG has far more aspirational properties in locations I like to dump points at compared to Hilton
- SPG has upgrades as part of policy (practical application is, of course a bit different). Hilton has jedi-mindtrick language about upgrades and doesn't offer them, as a matter of policy.
- Welcome amenity bonus, SPG has 500 points (except 4P), which is usually about 5% of award stay value for that type of property. Hilton has a variable number of points based on type of property. The value of those points is roughly 2% of award stay value for that property.
- SPG has cash and points. Hilton has a broken computer system that often prices things in Dinars.
- Hilton has "miles + points," SPG has points that are significantly more valuable than miles.
- SPG has the Lurkers. Hilton has a person in the background who PMs you and then assigns things to folks who rarely follow-through.