What some are saying is that a controlled laboratory test does not always relate to real world performance. The three failed rounds, in succession, used by the FBI (and chosen due to their performance in gel) are proof of that.
Penetration is needed. Something like Glasers do a good job transferring energy and not over-penetrating, however, they have trouble penetrating deep enough for a "stop."
If penetration was the only desired quality of a good round, everyone would recommend FMJ's since they are the best penetrators. However, there are a variety of qualities we look at in determining a good "duty" load; penetration is simply one of many. One undesirable effect of rounds that penetrate really well is that they tend to overpenetrate. As Clint Smith has quipped, "Every round you fire has a lawyer attached to it." If you load up with FMJs, and justifiably shoot an attacker, but one of your rounds goes through and through, and hits a bystander...you're liable for that.
Having said that, most modern JHP ammo, in popular defensive calibers, penetrates sufficiently to hit vital areas from a variety of angles, while at the same time reduces, or even eliminates overpenetration. They also confer other advantages, such as a larger wound.
What I look for in a round is one that is a proven round. One that does sufficiently on a gel test, but also has a proven street record. There are many rounds from various manufacturers that meet this requirement. I personally carry Speer Gold Dots in 124gr +P in my 9mm, and the same Gold Dots in 135gr +P in my .38Spl. Both are proven rounds, that sufficiently pass gel tests (though I don't think either completely passed the FBI tests). Something about the FBI tests. They set the bar VERY high. And they test a variety of situations that the typical civilian will rarely encounter.