My recommendation is to use psfMod on a hacked supported Android phone (if you already have one or planned to purchase one).
The TI-84 calculator is also a good choice, but due to the price unless you have a need for the calculator (other than jailbreaking) I wouldn't buy it.
X3max and the P3GO dongles are some of the more "high-end" clones out there. If you decide to get a Teensy then save your money for the Teensy ++ version.
Just compare the features of the different devices you want to choose from. Most of them can be flashed with psgroove, usually the main difference is how much storage/memory is available on the device. More is better, meaning you are more likely to use future software/exploits that might require more space).
If I were you and were looking for just a jailbreaking device, I'd go with a P3GO or a x3max (P3GO looks pretty sexy to me).
we have OpenKUBUS AT90USB1287, either 8 MHz or 16 MHz we dont know... We took a lot of different Hex Files, but nothing worked out.
we plug the USB Dongle into the PS3 Slim 120 GB FW: 3.50, turn it on and quickly press the eject button, now the LED on the Dongle is lightning green, but nohting else happens, just the normal startmenu appears...