DMPS tends to provide a smoother ride, especially in the early months of detox. Cutler says most people do fine when taking it every 8 hours for a long weekend along with plenty of antioxidants, etc.
DMSA is quite good for lead but tends to be harder on those with some immune system issues such as candida. I've done okay with DMSA but a female friend can only do occasional rounds without problems. She does well on DMPS + ALA.