I do not like Lenovo, especially the touchpad. Perhaps it depends on the Thinkpad model, but the one I have on a work computer (not my main work computer, a Dell Latitude) is very sticky (does not respond well & sometimes jumps to a completely different point on screen) & I don't like the texture. If you read the review of the Linux Thinkpad (linked to above), you'll see that they rated the touchpad relatively low (7 - I would have rated it lower for my computer), & comments left by readers also rate it low.
I've done google searches & tried adjusting various settings, & it just is nowhere near as good as either of the Dells I have worked on over the last 7 years (inspiron & latitude. The Lenovo DVD player door is always coming open. There are other smaller issues with Lenovo & unless Lenovo changes dramatically, I will never buy another. (Another minor issue: The Alt & Control keys are reversed (from most other manufacturers) on the Lenovo, but you can remap them fairly easily; do a google search).
I wouldn't claim Dell is a wonderful computer (I also had an Inspiron & learned a lot about laptops because of failure of multiple parts, all under warranty - I extended the warranty because of the problems; the Latitude seems better in this regard) but it seems a better computer than Lenovo (or HP - I had to disassemble a family member's HP entirely to replace the screen; I was amazed how flimsy everything was & it was a small miracle that it actually worked after I reassembled it. On a Dell, it would have been far easier to replace the screen.)
Macs have fewer repair issues (according to Consumer Reports) but I've also heard that Mac is moving in a direction of computers which the owner cannot repair themselves. At least in part, this is due to the ever shrinking computer (esp. in terms of weight & thickness). If I decide to buy another personal laptop in the computer, I will certainly take into account how accessible the internal parts are & am willing to have a heavier computer as a trade-off. I'm hoping it doesn't get to the point where no computers are accessible.