According to the Check Point Life Cycle Policy, the 12400 appliance reached EOL in Jun-2022.
The successor of 12400 is 15400 which End of Sale was Dec-2022. 15400 appliance is still supported (EOL) till Dec-2025.
For 15400 appliance there is already known successor - 7000 appliance while EOL of 7000 appliance is not known yet, since the successor of 7000 appliances is also not known yet (is currently the latest model).
7000 appliance can have up to 2 NICs, while original 12400 can have up to 3 NICs. This might be problem if you are using more than 8 Fiber ports on current 12400 appliance.
As always, the costs are the main key player. If you want the cheapest option, use VMs, or open servers.
If you have a bigger budget, try to check 7000 Plus appliances.