It's up to you to decide which one suits your needs.
Official drivers often have better support for drawing such as customizing your pen pressure, program specific options, shortcuts, click intervals, etc and should be able to provide support in case you happen to have some trouble with your drivers. If you are inexperienced and want to use your tablet for other stuff than osu! I would start off with these.
https://www.gaomon.net/download/ - gaomon drivers
Unofficial open-source drivers are used for their lower latency/smoothing which makes your cusor more responsive and feel less laggy but makes the cursor less stable and are very specific to osu!. You can also customize how much smoothing you want if that's your thing. They should also make it easier to customize your active tablet area. Some of them do not officially support your tablet though, so it might take some effort to get them to work properly, but it depends on which one you choose. There are a few to choose from.
Links:
- https://github.com/InfinityGhost/OpenTabletDriver - low latency, portable, cross platform driver that should support your tablet but does not provide customizable smoothing filters out of the box. Actively being developed. I would recommend trying this one if you want to try a custom driver as this one can be run without installation and supports your tablet.
- https://github.com/hawku/TabletDriver - the original low latency custom driver, comes with smoothing filter and anti-smoothing filter but does not work out of the box with your tablet. You are pretty much on your own if you have some trouble with getting it to work.
- https://github.com/Devocub/TabletDriver - pretty much the same as hawku but provides additional filters, does not work out of the box with your tablet.