An alternative to the MAX9633 part is the MAX44246. It features the same 18 bit dual op-amp configuration in the same package, but the MAX44246 features a wider supply voltage range and consumes less power per amplifier.
The MAX9633 uses a SAR topology, whereas the MAX44246 uses a Delta-Sigma topology.
The MAX44246 also has a far lower input offset voltage rating and a higher CMRR than the older MAX9633 part.