There was a video (or maybe just a series of pics) posted some time back that described why full chisel cuts faster (more efficiently) than semi chisel.
Basically, if you picture the wood grains running horizontally, full chisel will cut the grain once & remove the chip. With semi chisel, as the chain goes deeper, you are cutting some of the same grains again a second time (less efficient). This is due to the rounded corner of semi chisel. So in clean wood, full chisel is generally better (more efficient), all things being equal.
Conversely, if you have dirt or debris in your wood, or very dry wood, it will damage full chisel worse than semi chisel. W/O that corner, full chisel becomes worthless fast. Semi chisel has some redundancy in the cutters that full chisel is lacking.
That is why they make different cutters for different conditions. Your sharpening style and proficiency may also influence your decisions.
I usually cut clean wood that still has sap in in (which lubricates the cutters). That is why I prefer full chisel and square file. Full chisel will stay sharp for a long time in clean sappy wood. Your needs may be different.