Don't take the t series. Lenovo basically transformed this to pure trash. The only thinkpad series that lives up to ibms quality is the x series. Truthfully I wouldn't by thinkpads anymore. The only notebook you can by nowadays is the MBA.
So, no, the current t520 is not as well engineered as those old ones, but it's still better than the vast majority of its peers. And you get some great deals on refurbs and open boxes on outlet.lenovo.com.
Current MBA is only 4gb ram. That's a deal breaker for me.