I only used the Couch to 5k so far but it's the free version. The only thing I could see different with the purchased one is the ads are gone. Once I hit start and turn my music on, I don't touch it again so the ads don't bother me. Maybe you can try the free version and see if it works good enough for you?

Good luck on starting, I'm doing Week 3 Day 1 on Monday. I'm loving it so far, I hope it continues!

Yes, I did regular C25K until like week 5 last year (then came the snow and that was that because I hate running on the threadmill) and am now doing Zombies. I like both, though having the storyline element in Zombies is a really great touch. The thing about Zombies is that it's more about getting you moving than about getting you running: there are a lot of "free form" elements where you decide how much you run (so, for example, you may only have 30 seconds of running and then 90 seconds of walking in the second week, but then at the end you have a 10-minute free-form run where you decide how much you run and how much you walk). I can see people really disliking that element.

I used the free podcasts from the NHS. No ads. Weird music. Encouraging coach. Americans may or may not like the English accent. (I'm American but I've lived in the UK for so long I don't even hear it much anymore)

I've never heard of the zombie one.. I'll have to look into it.

I have the zombies 5K one but haven't tackled it yet. I did, however, do the regular Zombies, Run! app awhile ago and thought it was terrific!

I'm using the normal one for now but definitely plan to get the zombie one after I finish. The one I have (active.com one) DOES have a zombie trainer option but its pretty cheesy. Really love the program though