patricej

are you already sure you want to get well into sewing, and that it will hold your interest "forever?"
if not, i recommend you start with a big-box brother model.
if you find you don't enjoy the craft as much as you expected you will not have a lot of money gathering dust.

i wouldn't buy a used machine online unless it was located near enough for me to give it a hands-on test drive.

if you can afford it, consider investing in something that's a lot more than you think you need right now.
trust me ... you will grow into it before you know it.

pick a brand with a dealer near you that provides service and repair services, too.

my personal preference for sewing is anything janome over anything else.

you haven't said what your budget is, so i hesitate to recommend a specific model, but here goes. i'm afraid all my recommendations cost a lot more than the S5. keep in mind, though, that i'm thinking "forever machine." the models you listed don't have what it takes to be "forever." you'd outgrow them sooner than you think.

you would never regret buying a janome memory craft 6700.
it strikes a good balance between the machine i am currently drooling over (Continental M7) and something comparable to the S5.