I use one of these:
as my go-to for "dependable" readings. It's affordable, consistent, and fits in any glove box or pocket. I compared it to other fancier, more expensive, and theoretically higher accuracy gauges and got similar read-outs. It resets itself each time you use it, which helps convince me that it's trying to be accurate. I've probably had it 10 years, and I have yet to change the battery in it.
I also trust the analog gauge on my tire inflation air tool. It agrees with my little digital gauge. Of course, it has such a small face on it for such a large range that it's give or take 2psi.
I have a 12-volt (cigarette lighter) air compressor that will shut off at whatever pressure you set it to. The built in digital pressure gauge does not agree with the two above, always reading 3 or 4 psi higher than they do. But, knowing this, it's easy to set it a few psi higher and forget about it.
And I have one of those dirt-cheap stick ones kicking around. I tend to leave it in my wife's car, so I don't have to go find another. It's neither accurate, nor does it read high enough for my other needs - like bike tires at 60 psi - so it's just there to give an indication of whether or not that tire that looks a bit flat really is or not. They're cheap, and if I had a bunch of cars on the road at the same time (more than I already do), I'd probably spend a buck and put one in each for peace of mind.
Do with as you will with this information. I'm not trying to sell anything.