Logos is a powerful but potentially expensive investment. They have a huge range of materials available and allow for extensive research and would be my primary source for serious Bible study.
For me, one of the most helpful features is that I can copy and paste quotes from these resources into my sermon notes and it automatically inserts proper citation (author, title, publisher, page number, etc.) as a footnote in Word.
Logos has mobile apps available for Android, IOS, and Kindle Fire, desktop versions for Windows and Mac OS, and as a web version that will work from any internet browser.