This lady has compared seven types of decreases which lean to the left. As you can see, there are only two of them that look fairly decent-#3 and #7, which is her own creation.
However, on socks-when you're making the toe-you decrease on every other round, and I've noticed on that round that the left-leaning decrease (most use ssk) is bigger than the stitch on the following round, which makes that side look-well-slightly wonky compared to the other side, which looks neat and tidy.
I'm trying #7 now, which is a bit involved-but not too, and I'll see if it comes out any less wonky than using ssk or skp. I wish I could find a left-leaning decrease that will match the right-leaning decrease when you're only decreasing every other round.
And, rather than call it that long name that she calls it, I'm going to call it Nona's xk2tog-which stands for Nona's crossed stitch knit two together.