For an alarm while at home I saw a clever one the other day, buy a wireless house alarm and fit one of the pir sensors under your seat, when the home alarm is on the pir is armed, if a Scrooge takes your bike the alarm will sound as soon as the pir is more than 100 yards from your house. A friend sticks one in his van at night, has the added bonus of telling him if a scooter breaks in to his van as well.
Obviously this only works while the van is at home net the main alarm box.
When I had my triumph I had a dirty great abus lock, and ground anchor concreted in, they are all rated on sold secure rating if I remember correctly. Don’t bother with anything that has a barrel lock.
Motorcycle news did an article once where they parked a bike in Cambridge next to a cafe, alarmed and locked, then they drove up in a van and two guys lifted it and put it in the van, alarm screaming but not one person from the cafe moved or called the police.