How to fix and avoid micro USB connection issues?
I only have hands-on experience with the Nexus 7 2012 and 2013. In both of these devices the USB connector can become as you describe: charging is intermittent and might only work with some cables and when held at a certain angle.
I found the issue is caused by the solder connections of the USB connector getting loose. Re-soldering (re-heating with some flux and very little solder) the connector pins can solve this issue. That might be a temporary solution though as the design is such that stress can occur on the solder joint.
If you have no experience with soldering such small connectors then practice on some PCB that you no longer need. Of course you will need a soldering iron with a very small tip. Consider that you could ask a local phone repair shop to do this re-soldering for you, it only takes a few minutes of work.
USB-C is indeed a more robust connector however note that in what I mention above, it is not so much the connector itself that causes the issue. What causes the issue is stress between the PCB on which the connector is mounted and the connector itself.
So a different design for the connector and/or PCB might solve that. There are many devices that do not have the issue despite having a micro-USB port.
Consider buying a device with wireless charging so that there is no need to always use the USB connector to charge the device.