Do you have a specialist sewing shop within travelling distance? It’s best if you can ‘try before you buy’ to find something that feels right for you. Also, they’ll have someone who can service the machine and sort out any problems. Unfortunately, I don’t have anything like that remotely local, so I ended up buying from Amazon but it was on a very good offer at the time.
I’ve got a basic Singer as my back-up machine and a computerised Brother as my main machine. Their Innovis range is excellent.
The slightly more expensive models (not basic) usually have a built in needle threader which, once you’ve got the hang of it’ is the most marvellous invention when your eyesight isn’t as good as it once was! Threading the needle is child’s play now.
Singers are now made in China and I’d be wary of anything but the most basic version as I think they’re less robust than say, Janome or Brother.
If you really only want a very simple but reliable machine, a second hand Bernina would be your best option as they will last forever, need little servicing and a basic model is fuss free.