Do you use an external aerial?If you want a standalone device, they can be roughly categorised.
Cheapest is your pretty bog standard self-contained hotspot device which most carriers will sell you configured for their own network. They work, but don't expect many configuration options (some can be configured if you know about terminal access, and are willing to play with the barebones linux installation, but they're not high power devices so are still pretty limited).
Next are your more dedicated hotspots, things like the Netgear AirCard, which allow you to add their own external aerial. I personally use an older 2/3/4G AirCard when I need access in the middle of fields (The newer version only drops to a minimum of 3G).
Then you're into routers designed for more permanent installation.
I use a Teltonkia RUT-xxx at home, which again drops to 2G, whereas as the newer RUTX-xxx only drop to 3G.
The RUT(X) devices are aimed for industrial use, and they are highly configurable, but some configuration options require using terminal access, so not really for the non-nerdy types.
My biggest issue with the RUT I use (and it applies to all the range), is if you configure a VPN, you either have to go in manually reconnect it after connection loss, or write a script to do it automatically, as the manufacturer doesn't see why it should automatically recover, which means on connection loss, you lose all internet access.
The next step above that, is more configurable routers like some of the Draytek 4/5G routers, but they're another price level up.
Something not mentioned, is if you're a reasonable distance away from the nearest mast, bad weather will affect the signal.
At home, during quiet periods, I can get 20+Mbps on speed tests.
During busy times, that'll drop to around 5Mbps.
During heavy rain/snow, it can drop to less than that, but it'll also generally drop from 4G to 3G.
For anybody considering moving, I would suggest buying pre-pay sims for all the networks, load them with some data, run each one for a couple of days, and run a few speedtests at different times.
I found at home, although O2 gave the best signal, it had pretty poor ping test results and not that great bandwidth.
Vodafone didn't have as good a signal, but was consistently better on ping tests and gave more reliable bandwidth.
I didn't even try EE, as I know we were borderline for 3G signal, let alone 4G.
Once you know what network gives you suitable performance, then start looking at what deals you can get either direct, or via the various MVNOs - UK MVNOs: a guide to virtual networks (uswitch.com)
Although it's worth mentioning, an MVNO may not give you as good performance as the actual network operator. I know I use GiffGaff a lot when out and about, and for normal use it's fine, but if you load it up with a few computers/devices, I have found an O2 sim will often give better performance.
It makes a huge difference.
We have virtually no signal here with EE but an external aerial under the eaves makes all the difference.
We see no drop off with weather. And it rains continuously.
There are virtually no people where I live so the mast gets very little usage which helps.
In work we used to use Airband. Basically a microwave dish on the roof pointing to a transmitter the other side of Swansea bay a few miles distance. Every time we had heavy rain the signal would drop completely. Which is Wales would happen rather a lot.
I find 4g much less effected by the weather.
This is the type we have - or similar.