What do most people use to work with SSIS packages since VS2015 UI is buggy?
You can post on connect with any version and I would encourage you to.

These issues aside I think the only sane way to work with ssis is to use biml to write your packages and compile that into ssis.

This means you don't need to keep going into the properties of each task ad-infinitum- if you want to see how a task is configured you scroll down in the biml and look.

It is a bit more work upfront but as soon as you need to make a change or look at an old package it will pay off dividends.

There are other advantages like easy source code management, comparing biml files for changes is much easier than the raw ssis xml that changes id's every time you press "build".

Forget writing ssis packages using the ide and use it to debug packages when you really really need to .

Just to add on that when you experience the pain of being in the script editor ide and needing to close it down, close down th script properties, go into the data flow and look at the properties of a destination task and then go into the mappings tab to then close it all back to go back to the script task you realise that native ssis development is horrible!