Martie, for what it is worth, I did the 5:2 several years ago and am on my 4th week with BSD, so have done both. I find the BSD easier….less hunger, more flexible, easier to plan around. On 5:2, even though I was already low carbing, I found going from an “eating day” to start all over again for each “fasting day” tougher. I now find it pretty simple even to just eat one decent 500-600 calorie meal a day and have soup or a salad for a mini meal for the other. No breakfast.
MM recommends not doing back to back fast days on the 5:2 but I found Day 2 if done back to back much easier….its the first day that was always the challenge. With BSD there is only one first day….all down hill after that. And oddly, those that have been on BSD for a while and have a “off or binge day” say getting back on has not been a problem.
Each person has to decide what works best for them…but the big advantage of having these forums is getting the real life experience of lots and lots of folks that have tried lots and lots of strategies. Do know that of course you are getting a bit of a bias….because we are on this forum because we have found BSD has worked best for us. For me it is a god send and really opened a door I thought would never be available to me.