Hello Denise and welcome to the ArtRage forums 
Ask half a dozen digital artists this and you will likely get as many different answers!
Myself I’m a Wacom fan and have been for a long time. More particularly their Pro line of tablets as they are what have superseded the old Intuos line, which I still use, and share the same tablet Driver still.
Yes, they are at the expensive end of the market but if your budget can stretch to one then why not treat yourself! If something disastrous were to happen to mine I would replace it with another Wacom without hesitation!
In truth I'm not sure there is much difference these days between tablet makes when it comes to the actual hardware, pressure sensitivity, response times, etc…
The only thing in respect to the physical tablet that I couldn't work without is the 'Touch Wheel' on my Wacom, perfect for zooming & rotating the canvas on the fly as I work.
The pen also has Tilt sensitivity, i.e it knows how far over it is leaning as you draw and that it needs no batteries.
But what I really like about the Wacom Pro line are the drivers.
Wacom drivers tend to be the first a graphics app developer will consider when doing their coding.
All the Wacom tablets keys, the pen buttons and the touch wheel can be given unique functions that are specific to the app you are using at the time. Switch to another app and you can set different functions for the same keys. And it will remember for the next time. Do not underestimate how tiresome it can get if you always have to rest hot keys just because you switched apps!
Also all your custom hot keys can be saved as a backup file, so should disaster strike its really easy to get everything back just the way you had it.
As for size, I'm very happy with the Medium. I did considered the Large but the larger "footprint" of it on my work area (and yes the extra money) tipped me towards the Medium.
If you are coming from traditional painting/drawing and are used to using broad arm movements as you work, then the Large may feel a bit more natural.
Wacoms also work well with multiple monitors and mapping what area of the tablet works with which monitor. Or you can just assign the tablet to one monitor.
But anyway whatever make you go for take your time, look at what’s out there and consider what your needs are likely to be and your budget.
Maker Of Replica Macoys
Techie Stuff:
ArtRage 6.1.1 ~ 15" Macbook Pro ~ macOS 10.15.7 ~ 4 Core i7 3.1GHz CPU ~ 16GB RAM ~ Wacom Intuos4 M