I've had great luck with Thinkpad T420. I bought 2 over the last 2 years for about $225 (USD) from amazon. One of them i run linux mint without issue - my daily

I've had great luck with Thinkpad T420. I bought 2 over the last 2 years for about $225 (USD) from amazon. One of them i run linux mint without issue - my daily driver. The other one i kept with win7 (for kid as their school machine). I did replace the battery on one of them for a smaller physical size, and it apparently boosted the duration/power...so the original battery must have been aged. I can't complain because the replacement battery - again off of amazon - was around $50 (USD). Overall quite happy with T420 and would purchase theme again. (I have no experience with any other thinkpad models.) I hope this helps!