@pluralistic Not sure if I understand the question correctly. If you want to preserve the timestamps and such, use -a. This will fix the copy on change issue (timestamp changes on source->copy) if you don't want to rely on timestamps, use -c (slower, reads source and copy)
My personal rsync command is:
>> rsync -abzO --partial-dir=.rsync-partial --force --ignore-errors --delete --backup-dir=/backup/archive/`date +%Y-%m-%d` source/dir /backup/snapshot/<<<