im not sure about 29.42 yet but 28.32 used to be a good compromise between performance/stability.
you know this depends on your own system, testing is best thing to do.
i would recommend you to try with the officials 21.81/83 (mostly if you got hard stability issues), 23.11, 28.32 and 29.42 - actually the last versions

.
maybe someone can help you with leaked versions since im not trying with them for a long time, nor i think its worth anymore, in the case you not got stability issues.