Hi,
Redhat Enterprise Linux would be a much better choice. RHEL 3 is the most compatible for Synopsys tools. Refer
h**p://synopsys.com/products/platforms_roadmap.html
Recent tools also support RHEL 4. These are extensively tested. Fedora provides the bleeding edge software, many of them will not be as stable. Also RHEL have longer support cycles providing stability, compatibility for an IC engineer's toolset. If the you feel the support costs are higher, you can go with Cent OS 3 or 4 which are binary compatible to RHEL and built from same sources and constantly updated with their RHEL counterparts.
The preferred choice would be RHEL 3 update 8 or corresponding Cent OS 3.8 unless all of your Synopsys tools are very recent.
Regards,
venkatesh