From personal experience, CP Optimizer beats the crap out of other constraint solvers. Its API is... well, a bit rough, but it's incredibly fast and the support

From personal experience, CP Optimizer beats the crap out of other constraint solvers. Its API is... well, a bit rough, but it's incredibly fast and the support is top notch. I can't really speak for other IBM products, but I suspect they generally align with your perception here.