Not really sure I can give you a great answer on most of this, but I have been using Laravel for refactoring a very complex application with many different databases being used at many points, and laravel has been amazing with it. Having a quick check I can see there is an oracle and mysql driver, but for mssql this is the best I could find:

http://forumsarchive.laravel.io/viewtopic.php?id=155

I have quite a bit of use with symfony, and I personally found the ORM doctrine very hard to work with (especially in comparison to Eloquent), but then this could just be me being slow on the uptake.

I hope this answers at least part of your question!

Cgoosey1 Thanks for your answer. I will review the documentation while waiting for other replies.

I have developed an application that used both MySQL and Oracle for different data and had different logins based on LDAP authentication and I am working on 2 others currently replacing legacy systems and/or integrating them with new systems as needed. I ended up writing a package jfelder/oracledb for oracle access. It is rather easy to use multiple databases with a simple connection keyword, DB::connection('oracle')->normal_sql_stuff_here or setup the connection property in your model to use the correct connection.

HTH