I'm currently trying to develop a similar game to Osu! for a project in my university and want to find a device (tablet) that will things easier for me, I saw [suspicious link deleted by moderator] and I think they are fine options. I'm fairly new to development, any suggestions that could make my experience a little bit easier and fun? Thanks! 

A simple rhythm-based game like Osu! won't tax any reasonably modern device.

Even decade-old hardware can run rhythm games.  One game I was on for the Nintendo DS (with a 66 MHz processor) included beat-based rhythm games, and they had no performance concerns.

Of course, you can write terrible code for any project that runs slow, but that's nothing to do with the type of game you're making.  What you describe can be done without worrying about the hardware.  Buy some tablets, make the worst one your minimum spec, and start developing.