Tank or tankless?

We recently started noticing a melting plastic smell in the basement that appeared when someone was taking a shower. Plumber came over, looked at the tank (it's nine years old), and said that the insulation was probably melting inside the tank and that it was time for a new one.

He gave us two quotes: and AO Smith 50 gallon tank for $2,600, or a Navien tankless system for $6,000. I'm kind of leaning towards the tankless, but some research led me to r/plumbing where it seems those guys hate Navien--though it does seem that they would since that is a more DIY subreddit and Navien only deals with contractors.

For reference we live in a 1,600 sq ft house with two full bathrooms and two little kids. What's the opinion here? The tank seems like the classic choice, flat rate, you know what you'll get, probably replacing in ten years. The tankless comes with a $750 rebate and other tax benefits and supposedly lasts up to 20 years but has a lot of maintenance? What are people's thoughts?