Well TXL and GXL are both commonly used by OEM's. I believe I've read that most of the Euro brands favour the GXL with the domestics favouring the TXL.
Here's a good read about the differences.
Wire Selection Guide, GXL Wire, TXL Wire, UL 1015, MTW
I used the cheaper GXL wire. Only difference was the thickness of the insulation on the wire.
Riddler