This is the time period that coincides with a higher level for MTG's popularity. All of these sets have affordable packs (paper), and I have a solid selection of online. These are the planeswalkers I have online today.
I have all ten guild commanders for RTR block.
I have all but one of the Theros commanders.
I also have the wedge commanders from KTK (the set).
Battle for Zendikar:
Shadows over Innistrad:
This is a solid casual selection.