I prefer EFI Live to HP Tuners because it allows you to swap segments which allows you to make major changes. When I was buying HP wouldn't let you swap segments. A segment swap allows you to take the programming to run one piece of equipment and stick it in your computer which was running something else. Using this I was able to install a much stronger 4L80E transmission in my truck to replace the rubber band 4L60E transmission. However, HP Tuners is an excellent product. No idea how it compares to SCT as I've never used it. HP Tuners does allow you to do things EFI Live won't though. A buddy of mine used his version of HP to turn VATS off on my daughter's 2001 Malibu, which eliminated the problem these cars have of just dying for no apparent reason. EFI Live does not support this as it can't talk to the BCM. If HP is supporting the LS now, I would buy it.
In fact, if HP Tuners is supporting the LS, you now have the capability of swapping the factory engine for something else because you can make the computer talk to whatever engine you install.