Are you assuming 1 Accor point = 1 Hilton point = 1 IHG point?
The generally accepted valuation around Flyertalk is 1 HH=$0.004, 1 IHG=$0.007, 1 Accor =$0.022.

For a non-American member, HH is indeed good value among hotels:
- 8,000 e-rewards = 7,000 HH, or ~$3.5/1k e-rewards
- 10,000 e-rewards = 4,000 IHG, or ~$2.8/1k e-rewards
- 6,000 e-rewards = 1,000 Accor, or $3.67/1k e-rewards, but not redeemable on rates discounted >~25%

On e-rewards.com, cases can be made for each:
- $125 e-rewards = 7,000 HH, or ~$22.4/$100 e-rewards
- $100 e-rewards = 7,000 HH, or ~$28/$100 e-rewards, for HH referred and DL-grandfathered accounts
- $100 e-rewards = 4,000 IHG, or ~$28/$100 e-rewards
- $60 e-rewards = 1,000 Accor, or $36.7/$100 e-rewards, although not redeemable on rates discounted >~25%

Note that Accor was a more attractive proposal when it joined the program a few years ago and the euro was stronger, as their internal valuation remains 2k Accor = 40 euros; the exchange rate used by their non-eurozone hotels is nowadays updated much more frequently and fairly close to reality, whereas in the past there were some opportunities to be had in countries with rapidly devaluating currencies...

As it is easy to get more value out of a HH point (points & money mostly), possible out of IHG (pointsbreaks!), and impossible out of Accor (fixed ratio), I consider the values for those 3 major chains fairly comparable on e-rewards.com, as it should be, factoring in the respective restrictions and advantages.
Club Carlson redemptions are obviously terrible value, not having been adjusted post-devaluation; CC to me is showing all the signs of a rudderless program on its way out, no wonder the chain is up for sale.