The JTAG hack is very reliable, uses cheap easy to find components, and when you destroy soldering points, there are often a few alternates to prevent permanent damage to your box.
The glitch hack is exciting and interesting because it provides new options to consoles that were not exploitable.
It does however have some serious drawbacks. At the moment, you need to buy/build a CPLD board and programmer, and it's going to take a lot of trial and error to get it booting reliably.
I suspect this will make JTAG consoles more desirable. The glitch hack will allow far more consoles to run unsigned code, which will get more people involved in the scene, and those people will eventually want consoles that boot fast and reliably.