Since this is a IHG forum, and I really don't want to go all over the board, I'll compare the HIEx and Hampton Inns. These two are the closest apples/apples comparison from my experience. Also, for our work, my fiancee and I are most likely to travel to those brands.

In my travel, Hamptons and HIEx's are most likely to be available as franchised business/family-traveller hotels in cities of all sizes (and # of stoplights). Hampton Inns are more likely to be identical from one to the next. Holiday Inn Expresses are more likely to be all over the quality/hospitality spectrum, although the majority stay in the middle/middle-high end. In the end, though, customer service is enforced by the franchisee (and Hampton's 100% guarantee does help in that end).

Both have a free breakfast buffet with cold items and hot, greasy protein. Hamptons do more branding with their breakfast-day names. HIEx's have the cinnamon rolls (which smell and taste great, but aren't the pinnacle of creation). In the end, each ends up being mostly the same stuff on your styrofoam plate. Hamptons have Breakfast bags, but I'm not a cellophaned fake-fruit muffin fan. There's a thread on the Hilton board about the Hampton breakfast buffet, but I find it pretty pretentious and snobbish. When you're in Cornfield, Iowa, and you have to have breakfast at 0600 before driving 30 minutes to an even smaller town, it's that or Sonic.

Holiday Inn Expresses are more likely to have reception/hosted evening events, although that's not very common. A very few Holiday Inn Expresses have had Platinum gifts. More have had Monday Night Football parties or the occasional evening reception. Hamptons have not, in my experience, had anything more than occasional grab-them-while-they-last cookies in the evening.

The room quality/amenities/furnishings are identical among all Hampton Inns, while Holiday Inn Expresses are more likely to vary. Hampton Inns tend to use darker colors and hipper signage, while Holiday Inns tend to be whiter and have whatever the franchisee purchaed. I've had great rooms in HIEx's, and I've had shower-curtain mold. Hamptons have been universally well-kept. The best Holiday Inn Express beds don't touch the Hamptons' king-sized beds. On the other hand, most Hilton beds don't touch the Hampton Inn beds. I think Crowne Plaza beds come closest.

Sadly, points is the category I care most about. IHG runs so many Priority Club giveaways that it's hard to pass up staying at a Holiday Inn brand and maintain my Platinum status. If I end up with Hilton Diamond status, I've earned it.

Given a head-to-head stay at a brand I hadn't seen before with points taken out of the equation, I would reccommend Hampton Inns' class and consistency over the spin-the-wheel Holiday Inn Express. Even if I'm not thrilled about the re-branding look, I like that there is going to be a re-branding, and I hope they really do a better job of updating and unifying the looks.