For me, the "vanilla" T-series is the best compromise for weight, build quality, and repairability. My personal laptop is a T480, and it's an excellent machine. Very portable, screamingly fast, very good screen (I have the high-res IPS variant).
If you want a bit more premium feel and lighter weight, the Txxxs (e.g. T480s) is a bit thinner than the regular T-series, and feels a bit sturdier (so I've heard, anyways; my T480 is no slouch here, either). It also has less user-replaceable parts, and is more expensive for the same specs. The X-series also fits here.
If you're going more for a luggable desktop replacement rather than small size, the P-series is what you want. I have a P51 for work, and it's an insane machine: 64 GB RAM, Quadro graphics, touchscreen, Xeon processor... It also barely fits in my laptop bag and comes with a massive 170-watt power brick. But since I work from home and drive into the office once a month or so, it's a great machine that gives desktop-level performance (including very good cooling) while still being at least somewhat portable.
If you want the Macbook Pro experience of premium feel, thinness, less ability to be repaired, and higher cost, go for an X1 Carbon. I'd still prefer the X1 Carbon over a Macbook Pro, but I'd prefer a T- or P-series over either of them.
There are some home/SMB-targetted models, such as the E-series; avoid those unless you absolutely can't afford something better. All of the ones mentioned above were designed for customers that maintain fleets of machines, which has benefits even for non-enterprise users.
The current models are very good, and are a big upgrade from the previous generation. Of course, there is always something nicer coming, if you want to wait.
I'm looking for a portable workstation, so I guess that would be the P-series for me. They're a bit heavier than my current Macbook, though; my 2011 17" MBP weights about 3 kg, while the 17" P71 and P72 start at 3.4 kg.
People already complain my laptop is too heavy. Maybe I should start looking at smaller screen sizes after all.
What OS do you run on it? I have a (personal) T460, but I'm looking to get a new work laptop, and I'm considering trying to swing a T480. I've had great results running Ubuntu 18.04 on my T460, but last I looked, the T480 was having some compatibility issues.
X-series is always a safe bet if you want something a bit more portable than the T-series, but with the same build quality. I don't know about the newest (x280), but I'm rocking the previous X270 and I'm really happy with it.
I also never see people mention it, but the L-series feels a bit underrated. I handled some older ones the other day and was super impressed by the build quality. I think they go for like half the price of T-s too.
L540s (4 or 5 years old now) used by the dozen in one of the places I teach, the managers have them as portable work machines. They seem reliable, they get a beating. Quite big 15inch screen, thick bezel &c.
The T range or the P range remain good recommendations.
The T is a little lighter but you lose some power/upgrade options, the P is kind of what the T used to be (both in terms of price and performance). The current gen' T is a slight lightweight but not a bad buy.
They have a bunch of ultra-lights/ultra-books/2-1s, but they aren't "Thinkpads" in the classical sense.
Not sure about a recommendation but stay away from T480s. My roommate has had so many issues with his that it has driven him mad. He's had so many things fail and had to send it in for repairs that he's used my old MBP more than he's used his new T480s. First, he had issues with battery (it stopped charging), then the internal keyboard failed (wouldn't get recognized) and now one of his USB ports doesn't work and his trackpad intermittently stops working. He still hasn't sent it in for a repair and is contemplating just asking Lenovo for a refund.
This is not an isolated incident... lots of issues with some new Thinkpad models. Make sure you do lots of research before you buy any of them.
I just bought an E485 (AMD Ryzen). I'm enjoying it thoroughly. The "E" series has integrated battery and fewer USB/data ports/less dock compatibility, BUT battery, drive, and RAM are all "user-serviceable" meaning not soldered in.
And I got a great deal with some discount codes, now expired... AMD Ryzen 2700U, 16GB RAM, 128GB NVMe drive, 1080p matte screen for $670 plus tax and shipping.
If I had more money, I would have gotten the A485 (AMD fanboy) as the A and T series are easier to maintain and have more features like keyboard backlights.
The P51 actually has a magnesium body, which I only found out because I was leaning it against some concrete walls in a parking garage while troubleshooting some equipment with it.
