Hi Randy, Well plugins are certainly getting better. Some of the modeling plugins can make it tough to tell a difference even.
I think the differences that we are hearing between the two mixes aren't as much associated with the type of plugins you are using, but more the processing decisions you have made.
Unfortunately there is just no way of telling from your test which are the better plugins. Of course we have our ideas and beliefs about which ones we like better, and sure we could pick one mix as being the one we like, but to say the type of plugin used was the determining factor to the way the mix turned out might be a bit misleading. The Waves mix can be approximated with the Sonitus plugs and vice versa.
Now, if your ears just flat out tell you that you like the Waves stuff better, and/or if it gives you more confidence to mix with the Waves stuff, then i say by all means get them. Ha! Im sure weve all NOT liked a plugin just because of the way it looks. This stuff is supposed to be fun too, so my vote goes to what ever makes the most enjoyable experience for you.