I agree with many of the comments.
Diamond Wooden Racks are good, but they can get beat up. Also, it is common in my experience for them to get gummy at the point the balls touch them, which often causes balls to stick to the rack (thus unfreezing when you pull the rack away). This crud can be scraped off, and that helps.
The Diamond plastic rack is excellent. I can’t compare it to the Delta rack because I have never had one.
I have not had success with the new fangled Predator rack. I could not get the balls tight. I’ve also noticed many bad racks at Predator events. That said, a guy I know who owns it likes it and seems to get a tight rack for a second ball break in 8b. Maybe it just takes practice to train your hands to manipulate the balls in it.
Cheap plastic ones suck and are a sin against the pool gods.
As [mention]iusedtoberich [/mention] said, the quality of the balls are key. With new balls and new cloth I can get a tight rack with any decent rack. When the balls are old, or heaven forbid mismatched, good luck getting a tight rack. If it’s a full rack and I am free to arrange them as I please, I might be able to find a limited number of good balls and freeze those ones to give a good break.
I also have views on templates.
With bad or mismatched balls, I like the Taom MaxRack (the poop emoji looking rack). I find the extra bits of plastic (more slots for balls) help corral the ones that are reluctant to freeze. The only downside is the extra bits are more things for balls to rest on post break, making it harder to remove the template.
I haven’t tried the new Pagulayan rack, which also has extra bits.
For a full rack with good balls I like the magic rack and the Perfect Rack (simple triangles) because you can still get a good rack and don’t have anything except the triangle shape for balls to sit on post break.