I have been with Vonage for years (like 2004 or so, maybe eariler?)
I also have my vonage router plugged into the phone jack of the house, so I have phones throughout the house, as well as having my modem, router and vonage device on a UPS battery backup, and one "old school" corded phone, so even in a power outage the wife has a phone (for about 3 hours till the UPS dies).
I have their cheapest plan ($20, 500 outbound minutes, unlimited incoming).
Same reason as you, wife wants a "landline". And for a while we did have mediocre cell reception inside, so was kind of needed. With Wifi calling though, it is not an issue at all.
I am getting close to getting rid of it though, she rarely uses it, I never do.
I have debated going to Ooma or Obi, but just never really looked into it.
I know magic jack used to suck. My dad tried it when it first came out (had to always have it plugged into a PC that was powered on) but have heard it has gotten better, but no idea on price.