Linux Looking for good work laptop

[Shana]

I'm looking for some recommendations or maybe feedback from people who used iGPU without dGPU.
The laptop wouldn't be for gaming (et does not count ) but mainly for processing large amounts of data (25 million+  json documents in mongodb database), frequent rebuilds of node applications and automated testing framework on top of all that.
Average ram usage 15Gb(not counting swap pages) but I'm leaning towards 32Gb to be safe from the system locks.
System Linux duh with a tiling window manager for increased efficiency.

 

Best picks I found are:  
Lenovo ThinkPad T580 (20L90024PB5P32) due to its mobility and endurance and I think it's the most reasonable one for how I intend to use this laptop.
Lenovo ThinkPad X1 Extreme (20MF000WPB2PP32) due to dGPU for media creation.
Dell XPS 15 9570 due to battery and performance.

Been reading a lot of topics, Reddit, etc and still can't decide. Based on feedback from reading it's like a lottery with laptops.
It's true that those laptops have their issues (low build quality for some models, coil whine, backlight bleed, some keys on the keyboard) that's why asking for more feedback maybe?
No limit on the money since it's work machine so efficiency matters.

If you are unable to find which configurations I picked for thinkpads, let me know and I'll list the parts for both.
Thanks  

Edit:
Thinkpad T580 configuration:

CPU: Intel I7-8550U 1,8Ghz-4Ghz
iGPU: Provided by CPU Intel UHD 620
Display: 1080p 15,6"
Storage: Nvme 512Gb
RAM: 32768Mb DDR4
Modem WWAN module 4G
Battery build in 4cell + 3cell external

ThinkPad X1 extreme configuration:

CPU: Intel I7-8750H 2,2Ghz
dGPU: Nvidia Geforce GTX 1050 TI 4Gb
Display: 1080p 15,6"
Storage: Nvme 2x 256Gb - probably in RAID 1
RAM: 32768Gb DDR4
Battery: built in 80WH

 

Edited April 2, 2019 by Shana

[RedBaird]

Neither Google nor DuckDuckGo find those ThinkPad (numbers).  Are they SKUs?

[Shana]

Just now, RedBaird said:

Neither Google nor DuckDuckGo find those ThinkPad (numbers).  Are they SKUs?

More or less, they are used to determine the configuration as those laptops are easily upgradeable.
Will add specs to the #1 post then.

[RedBaird]

16 minutes ago, Shana said:

used to determine the configuration

AhHH!  So your (numbers) could be unique on the Internet (for now)

[Smoky]

Im not really sure how much money do you wanna have for this.

 

Atm for work i have a Lenovo P1 here. 32MB RAM an 2 1TB SSD.  For Work i use an auditable software from Caseware.

With 25 Mio booking accountings a year (period is 3 years) it is not fast enough for me (Xeon E-2176M).

 

Have an eye on the interfaces. At the P1 are only 2 USB 3.0 .....

 

X1 vs T580 the T580 has a numlock an the bigger batterie then the X1 and the x1 is the better choice to travel with it.