I have the topeak as well and my issue with it is that due to the way it engages with the presta valve head, I find it impossible to put it on without deflating the tire somewhat. So it would have been interesting to see whether the other gauges also read 17 PSI after the topeak had been used.

I suspect your Topeak might have a worn gasket that leaks a little. If that's true, Topeak might sell spare gaskets. Personally, I have a Topeak Smartgauge D2X, and a Topeak Shuttle Gauge Digital. I definitely prefer the D2X of the two. The D2X appears very similar to the D2, with as I understand it only a few minor differences. The D2X is a pretty flat thing while the D2 is more cylindrical, the D2X gives the reading in PSI with one decimal, and it will measure up to 280 PSI, something I don't ever expect to use. The Shuttle Gauge is in my opinion a little bit more cumbersome, it has a lever so that it will lock onto the valve, which is useful, but I always worry a little that I might bend the valve by mistake if I use the lever a bit clumsily. The lever, plus the all metal construction, also makes it a little bit bigger and heavier, and I also believe more expensive. On the positive side, it has a pass through valve that allows you to attach a pump to the gauge, and turn any old pump into a manometer pump, or I can use it to verify that the pressure gauges on my pumps are accurate. That's certainly very useful, but 9 times out of 10 I will reach for the D2X. Just like the D2X, the Shuttle Gauge Digital shows decimals in the PSI readings, and it measures up to 300 PSI. Both gauges turn on automatically when you attach them to a valve, and will turn off automatically if the measured pressure doesn't change for a minute or so. Not sure if the D2 does that. Also worth knowing is that there is a Shuttle Gauge Analog, which has an analog display instead of a digital one. This one is a lot bigger than the Digital and I don't really see why people buy it. I guess some people hate batteries, or maybe they like the way it looks and keep it somewhere where it's clearly visible. I don't need that, after all it's just a pressure gauge.