It’s worth double checking that it hasn’t already got one fitted it may only be a case of reactivating. If not, most insurance companies tend to stipulate a CAT 5 or CAT 7. Seven normally includes a phone app, loss of signal, geo fencing and 24hr monitoring. Whereas five (the more expensive one) tends to come with all the same benefits, but you can add items such as a key tag, however both will still allow the car to start. If this is a concern you could also think about adding an immobiliser so no card/tag no start.
Regardless of whichever you choose don’t forget both will be subject to a subscription charge. When I had my CAT7 recently installed I paid for three years in advance which although I probably won’t have the car by then saved me a rather big chunk of money. Sorry I know it’s all a bit confusing so speak with your local auto electrical dealer I’m sure they’ll be a lot more informative than me, but as Greenman says before you do anything make sure you double check what your insurance company stipulates.
Hope this helps.
Greg.