If the CPUs are of the same class, then you can compare the speed apples to apples. That alone would push you towards the faster processors (4x8x3GHz).
The usage of your database might also be a factor. This about the "shape" of your data processing. Is it many smaller computations or fewer larger computations? Going off of what mrdenny said, and being that it's a transactional database (right? Since it's financial?) I would think that it's not so important to maximize the number of CPU cores sharing the same cache/NUMA node since the multiple cores are likely working on different tasks where the cache wouldn't play as large a role as it would in a data warehousing/data mining application. Having 4 NUMA nodes may actually allow increased throughput for memory access vs. 2 NUMA nodes in a transactional situation, where smaller threads can more easily be optimized to access the memory on their local NUMA node. Also, if the processors are the same class and the 4x8 is faster, it's likely any possible performance degradation for non-local memory access would be made up for by the increased performance/core.
If the CPUs aren't the same class, then you really need to look at some benchmarks to see if the "slower" processor is more efficient.
Also, consider possible future expansion. Are your choices between 2 and 4 processors in a 4 socket system? If you think that your demand for processing power might increase, having the 2 processors would leave you room to expand to an additional 2 processors if there are 4 sockets in the system.