I use to use Mr Tuffy's but found goatheads did penetrate those too. Also Mr Tuffy and Slime liners will eventually chaff your tube and rub and hole into it causing a leak so you have to sand down the edge that contacts the tube to a paper thin thickness to prevent that. I now use Panaracer FlatAway in my rear tire on my touring bike because getting a flat on a touring bike is a bit of pain with having to remove the panniers, then the fender, then the wheel etc, I don't want to be bothered.

But I did discover something interesting about liners, the Mr Tuffy and the Slime liners cut like butter when you go to trim them to fit, but the FlatAway was a pain the arse to cut.

As far as tire savors go, I haven't used those since the tubular days, they do work but not all the time. I still got flats but instead of 2 or 3 a week maybe 1 or 2.

In reality tires are suppose to be the first line of defense against flats. Once I got a set of Specialized Armadillo tires I never needed liners after that, and no goathead, or anything else, ever penetrated one of those tires in 15,000 miles of using those tires. I was so confident it the tires ability to not get a flat I switched to ultralight racing tubes after the first set of tires wore out. There are a few other tires too that can ward off Goatheads, but those I've found to be among the best and cheaper then others.