I have found some strange index selection anomalies in SQL Server which lead to bad performance. It seems this can be solved only in SQL Server. I already asked about it on the forum (no answer) social.technet.microsoft.com (topic “Index selection anomalies. How syntax impact on index selection”).
You can find all information about on the forum https://social.technet.microsoft.com/Forums/en-US/7b80a564-af64-4544-8b36-6ca19bc52e68/index-selection-anomalies-how-syntax-impact-on-index-selection?forum=sqldatabaseengine