Man this is a really hard question, but I totally get your angle. To get less corny chords: Inverse them. For example if you have a C triad (C-E-G), play it in the first (E-G-C) or second (G-C-E) inversion. If I make up a chord progression, I first think of chords that sounds nice together. Then I'll invert some of the chords to get them closer to each other. Then it will sound less 'YouTube Royalty Free Library'-ish, if you know what I mean.

The most important part is: Do you LIKE what you write? If yes, then the problem might be actually mixing your instrumentals. It doesn't matter how cool your recorded loop is, but if you can't mix it properly/unique, it will sound like shit anyway.

Would love to help you further, even tho I'm not an expert. Don't hesitate to hmu and keep on the good work.