I'd have to say the Trinitron, thats why i bought my CPD-G420. But if you don't want to spend the extra bucks, a Diamondtron is in reality, practically identical. Apart from me prefering the Trinitron's quality, i also noticed i liked the "Sony" logo better. But i only came to that conclusion after using it for a week and staring at it.
If you want to spend even less, get a 19" KDS Flat Screen. They use the Sony Trinitron tube.