Most people would reply that the Xlab gorilla XT cage is the standard. I have a Specialized Rib Cage that works very well and hasn't ejected a bottle on me yet. So that's a choice also. A bit of it can come down to bottle choice as well, as some just seem to be a bit more slippery. You probably have looked at that aspect already. One other thing I've done is take a regular metal cage and attach a strip of some leftover Lizard Skins bar tape to the mid section. The tacky grip worked quite well.

I have a just a gorilla I think its plenty grippy I sold my gorilla xt and switched it was to tight for me to grab while riding. I have a rib cage as well before that and didn't have an issue just wanted to go with carbon and got a deal for the gorilla.

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2019 T-Rex Tri Series

I have a hard time with my gorilla xt in the back. It's almost too tight. I'm giving it some time to see if it "loosens" up. Works well with my BTA bottle, but a little sketchy when trying to pull from the back. Nothing close to an ejection though.

I've had great success with the basic metal ones from performance bike. You can manually pull them in or out to change how secure you want your bottles. Simple.

x2 - the metal allows you to bend them to grip the bottles tighter, and they're about a fifth of the cost of XLab cages and the like. I've also seen people using small sections of grip tape on the part of the cage that contacts the bottles to get more grip.

Right now I have a couple of cheap Elite Sior Mio cages behind my saddle that hold bottles better than any cage I've used besides the metal kind, to the point of being almost too tight. I put a couple on my road bike too based on how well they worked on my TT bike.