Refurbed Lenovo ThinkPads - whats the "current gen"?

I'm in the market to hurl at a wall upgrade our badly ageing general use family laptop (Lenovo V110).

I've used ThinkPads in the past for work and due to their ubiquity there is a value to be had, I believe, in corporate refurbs.

However, it's been a good few years since I used one - think it was a T440 - and am looking for some advice on what the most recently obsoleted gen is that I should be looking for, or where people have found a sweet spot on price/performance. Any pointers?