I see recommendations for a X230, but I disagree. If you really want the best, it's a W520 or a W530.
In either, you can have 32G of Ram, and you can replace the default CPU with a Intel i7 3940XM cpu. But only on the W520 you will have a full size display port and (more important) an eSATAp connector.
On thinkpads, you can usually have 3 drives:
- a normal 2.5" SSD
- another 2.5" in the optibay
- a mSata in the WWAN port
But with the eSATAp connector, you can have 4 drives, one of which will be external - either connected to the side of the laptop or to the dock. Useful for backups at proper SATA speeds.
About the screen, the dock has extra display port connectors, and the internal LCD is
1920x1080, not high resolution but good enough. The CPU support vt-x and
vt-d, so external displays can be used with qemu vfio (I don't have a dock
yet, but I plan to do that soon)
If we are talking about CPU, in theory, a modern P70 is faster. But if you overclock the 3940XM to 4.6 GHz, there is no faster thinkpad on the market. Cf the results from:
https://thinkpad-forum.de/threads/199076-Projekt-quot-Das-Letzte-Thinkpad-quotThe only issues with the W520 on coreboot is the power consumption, which I hope to fix when I will understand better how to talk to the EC to properly disable the NVidia GPU like the default bios does.
With only the integrated 9 cell battery, I get about 4h, while putting my SSD into a similar W530 (same CPU) where I can do proper power management on the default bios, I get 7h (don't know how much precisely)