Once you’ve determined your budget you’ll need to consider both the kind of bike you have and the features you deem important.
A tracker needs to be discreet so matching its mounting options to your bike is advisable.
If you keep your bike locked up outside, or commute year-round, then waterproofing will need consideration. Look for trackers that have an IP (ingress protection) rating of 65 and above.
Connectivity is another feature you’ll need to consider. Cheaper options are likely to use Bluetooth to connect to your phone, which means a greatly reduced range compared to those that use GNSS (Global Navigation Satellite System), which are typically far more expensive. Remember trackers that use a SIM card that send’s information straight to your phone require a subscription.