There is lot to consider in re-org vs re-index. In simple words, yes, less than 30 % fragmented good to do re-org else re-index.

For example.you have 90% fragmented index, re-org takes more resources than re-index. this answers your question I believe.

If you are not sure still, here is a very great index maintenance job you can create which can understand your indexes and does the best.

http://ola.hallengren.com/sql-server-index-and-statistics-maintenance.html