I have had very poor results with the dry powder compounds that are supposed to dry fast. Usually takes a day before they are dry enough to sand without gumming up the paper. So why bother?
The premixed compound in a bucket works fine for me and that is all I use. Mesh tape is much easier to use and more reliable, so I have switched to it. I have repaired too many tape jobs by pros where the paper tape has come loose even years after application.
The corner tool is hard to use? No way! It is neat and fast and easy to learn. It may be that you have one that is too small; the "wings" on mine are about 4". I lay the compound on with a 4" putty knife or a wider drywall knife and run the corner tool down from the top to as near the floor as I can, and then up from the floor. Incredibly fast!
For more hints on working with drywall, read that topic on my website at www.bobf.info.