I prefer the falcon jtag over the other ones. It is usually a matter of preference.

As wise mod said i also do suggest falcons because it has a low risk of RROD as it is one of the later models.

Xenon: a xenon console is one of the first models made and is not worth buying it will only last about a month on average and not worth the money. I do not suggest you buy a xenon. Price Range: $100 to $150

Falcon: Falcon console are good quality console they have a low risk of RROD but it can still happen, i suggest you buy a 12v Fan mod just for piece of mind. The Falcon console was a remake of the xenon console in 2007. Xbox remade the xenon console using a stronger solder to keep the motherboard less vulnerable to RROD. I would personal recommend the Falcon as it is not to expensive and will last a long time. Price Range: $200 (on average)

Jasper: The jasper console is one of the high end console. Mainly because it has an extremely low chance of getting RROD many people usually buy a Jasper console because it is very reliable. I also suggest the jasper console because it is has a very low risk of RROD and will last. Price Range: $225 to $250

Slim: The xbox360 slim console is the latest console made by Xbox it has an intricate design to increasing air flow throughout the Xbox motherboard. The slim is the best console to buy at this current time is Will not get the RROD even if you leave it on for a year straight(proven fact). The only con to this is that it is also the most expensive console ranging in prices from $300 to $320.