Rational ClearQuest is not a product based on Jazz platform and not usually discussed in this forum, and you should direct your questions to the ClearQuest forum in the future.
https://www.ibm.com/developerworks/community/forums/html/forum?id=11111111-0000-0000-0000-000000000329
IBM normally recommends the latest version of the product (8.0.1.3 in the case of ClearQuest) since it contains the latest bug fixes and new features. Check the release notes of each version to determine whether any particular fixes or features of interest are in that version.
http://www-01.ibm.com/support/docview.wss?uid=swg27038259
If you have specific business requirement for the product, I would suggest you talk to a consultant before making the decision.