Here are some detectors I own, along with some brief thoughts. I will update this page as I collect more!
Radiacode
The radiacode 10X has quickly become one of the most popular detectors for hobbyists. While remaining at a reasonable price, it uses scintillation rather than a G.M. Tube, allowing for gamma spectroscopy. Basically, you can use it to determine what radioactive element you are measuring, given that the activity is high enough and/or you have enough time. It has some flaws, such as poor EMF shielding, but it is overall a killer device for the price point. If you like the idea of spectroscopy, but aren't stoked about buying from a Russian company, look into the Raysid or AlphaHound.
Ludlum Model 3
Commonly paired with a 44-9 pancake probe, the Ludlum model 3 is one of the most frequently mentioned detectors for those getting more "into" the subject of radiation. Its reliability and massive number of probes are its main selling points. Ludlum customer service is also great, and will help you out even if you picked it up second-hand (like I did.) The device is basically a brick and is completely analog. I'm currently working on a project to add some more modern features- Stay Tuned!
Plessey PDRM82
I picked up this detector off eBay because I thought it looked neat, and it was pretty cheap. This is a "Shit's fucked" detector, as in, if you can get a reading, something has gone wrong. It measures in centi-gray- 1 cGy is roughly equivalent to 10 mSv. I believe that the tube has a radioactive check source incorporated that tests itself. Once it decays enough, it might stop turning on. I think I could get around that by holding another source next to it during power-up? Who knows...
Rados RDS-30
This one was a cheap FB marketplace find. I'm super stoked about it, because they command a high price on most platforms, and I found it for less than $100. It is energy compensated, meaning that, despite being a G.M. Tube, the dose rate it reports should be accurate when measuring different radioisotopes.
