Suggested hardware platform

Somewhere in this forum, it was suggested that running on real hardware was best. That sounds like a good idea but the question that I have then, is what would be a good hardware platform for learning on? And what would be the minimum specs would be suggested? Android version? Memory? Display size and res? I assume USB is necessary? I suspect that not just any consumer device can be used as a development device or can it?

Any consumer device will work. However I prefer using the Nexus line because they usually get the latest Android version from Google.