I started with a F1 Shooting Chrony. It works well enough, but I did not like having to write down all the information by hand. I got the optional printer for it, but it was still a bit of a pain to use.
Then I got the Caldwell chrono and really like it. I have put well over 1000 shot groups across it. Occasionally I will have a problem when the sun is in a certain location in the sky, as any optical chrono will. The phone app is what really makes this chrono, though. No shot string statistics are available in standalone mode, all the data collection and statistics are done by the phone app. But, it has worked well for me. For the $70-$80 that the chrono costs, along with the free phone app, it will do most things I need.
I have a friend with the Pro-Chrono and he likes it, but required purchasing optional equipment to connect it to a laptop or phone. The adavantage of it, though, is that shot string statistics are performed in the chrono, no external connectivity is needed for that.
Then there is the Labradar. Several advantages to owning this. First, the chrono is placed beside the gun, not in front of it, so no chance it can be accidentally shot. This also means it can be used at ranges where you aren't allowed to go in front of the firing line, like a lot of indoor ranges. Lighting is not an issue as it does not depend on light for its operation. It can record the velocity at multiple distances in the same shot, for 223 it can record velocity as far as 75 yards, and farther for larger calibers. In fact, about the only downside to this chrono is the price.
And lastly the Magnetospeed. If all I shot were rifle, this would work for me. They have adapters that will work for some handguns, but there are some guns this simply will not work for.
Knowing what I know now, if I had it to do all over again (and the Labradar were available) I would get the Labradar. It was not available when I first started, though.
