Fusion360 is a very capable program, however if you're only planning on doing engraving, it would be very much overkill. It's best suited to 3D modelling, or where you want to create tool paths/G-code from 3D models.

I've only ever had a quick play with Estlcam. I found it pretty easy to use, but that comes with the sacrifice of it being a bit limited in what it can do. But all these programs are trying their best to compromise between simplicity, and capability. The more capable they are, the less simple they become, so that's not necessarily a bad thing.


The rounded corners is down to controller settings. In standard mode (G64 constant velocity mode), what the controller (well the trajectory planner within the controller to be exact) attempts to do is maintain the requested feedrate, but obviously it has to allow for acceleration/deceleration of the axis. When it approaches a sharp corner, it has to start decelerating one axis into the corner, while starting to accelerate the other axis out of the corner, which leads to move blending/corner rounding.
There are normally various settings to control how corners are handled. The blend option I'm guessing controls how much the machine can deviate from the toolpath/g-code. By reducing it to zero, what you're essentially doing is telling the controller you don't want any deviation from the requested toolpath, so to keep on the toolpath, the machine has to start/stop between each segment (some CAM and controllers will split arcs into small straight sections), which is what causes your 'juddering' on arcs.
Some controllers also have a Break angle setting, which sets the corner angle above which an exact stop should happen to ensure a sharp corner I.e if it's set to 89 degrees, an 88 degree corner would be rounded, whereas as 90 degree corners shouldn't.

There may also be an option to enable exact stop mode (G61). What that does is force the controller to not round/smooth/blend any move. It'll accelerate/decelerate on every move. It gives you the option of forcing the controller to create a sharp corner where needed, and then disabling it to smooth other corners to maximise feedrate.