Choosing between a chip and propane? I could give a better answer if I knew a little more about your truck. For example, is it an automatic, or a stick? Are you happy with how it runs now, but merely want more power, or are them some characteristics you'd like to change? For example, shift points on an automatic.
If you're happy with everything else, but merely want more power, then propane can/will give you more power than a chip. As was asked earlier, do you already have the ground work done, by getting a downpipe and exhaust, gauges, and intake?