I've discussed this with my patients, the ones who have spent time in both. They say that prison is preferable due to knowing where you stand ie your liberation date, which is the most important thing to them, getting out, however for the day to day routine, secure hospital is much better.
In my medium secure hospital, our patients have tvs/radios/computers etc in their rooms. Daily sessions on offer at the gym/football, cooking groups, gardening groups etc. A communal lounge with a TV, books and areas to socialise. They have a therapy kitchen and can order from the supermarket and can cook for themselves, as well as order takeaways at designated times. It's all about rehabilitation; to us, they aren't prisoners, they are patients.
Personally, I'd take secure hospital every day, but yes, the major downside is that you can be held indefinitely as opposed to having a lib date.