The Hitachi is SOOOO strong that I can't use it all the time, and I need pretty strong vibrations to reach climax. Also, the Hitachi has to be plugged in (Boo) and every time I have to clean it I'm worried about getting water in paces it doesn't belong. It's a fun thing to have around, but the Hitachi is definitely not something that I would recommend using all the time. Vibrations that intense, that leave you feeling numb after using it can't be good for you.
The Inspire is great, it's small and strong, but has to be plugged in. Also, the vibrations are a little on the buzzy side as apposed to being rumbly like the Hitachi.
The Mystic wand rechargeable is a nice and strong and doesn't have to be plugged in while using it. The vibrations are a bit more rumbly than the Inspire. This is my current favorite, but I am going to try the smart wand sometime very soon.