Best database for UNIX installation

Hi,
My application is for a large PACS used for research purposes only at our hospital. We are presently using CTN with postgres and, while I am upgrading the server, I decided to upgrade the DICOM server software at the same time. My intention is to install conquest on a SOLARIS 10 machine.
While I am getting everything together, I see that I have a choice of database software. In the windows installation manual, you compare the different choices of database software and it seems that postgres compares favorably to the other choices. Does this comparison hold with the UNIX installation? Would you recommend other database software instead?
Thank you.