What database software is best to build a database of thosands of subjects with many categories-for research?

The data base should use for research purpose, and shouls be easy to use. the researcher have to be able to take partial data from the big database. is has to have simple GUI/MMI. The data abous gifted childrens, their teacher an programs. it has many variables and many categories. I think SAS and SPSS are too simple for that. it had to enable statistical processing or convert it to SAS or SPSS format of data (to make the statisticall processing). so what is the best software?