Tuxedo Computers can get you a very good dev laptop for ~1500€ (64GB RAM, AMD/Intel CPU, NVIDIA/AMD graphics card). If you will be working in AI, I imagine you'll need CUDA (?) aka NVIDIA.
If you don't go for anything on linuxpreloaded (which I wouldn't recommend), it's good to check whether what you're buying has linux hardware support by checking the Linux Hardware DB. Even if you don't look, it'll probably work, but better safe than sorry if you're going to dump 1/3 or 1/2 of your months salary into something (depending on where you are).
For a distro, I dunno what level you are, but Distro Chooser can help you out with making a choice. My recommendations:
linux beginner
Linux mint. nice desktop environment, looks like a mashup between windows and mac, still missing advanced options, but quite customisable. comes with suitable standard software and cloud integrations (you can connect to a bunch of clouds), relatively up to date
Ubuntu is well-known, some proprietary companies even consider it "the linux" and only make linux versions for it. It's quite stable. However, it isn't my first recommendation anymore as they are going down a proprietary route. I'm not sure if they have ads yet, but wouldn't surprise me if they started.
desktop environment
This is the desktop suite, a bundle of packages that work well together on any distro, with its own look and feel. There are basically 3 camps:
windows look n feel
KDE: is the most known, is very customisable, has an abundant amount of themes, icon sets, login screens, fonts, and a well-sized userbase. They prefix many app names with "K". Ubuntu even has a distro version called "Kubuntu" with KDE on it
Cinnamon: main user is Linux Mint
LXDE and XFCE: look closer to windows 95 and windows XP, consume minimal resources. configuration is through the interface, advanced configuration through files
mac look n feel
Gnome: they are well known and source of flame wars (gnome vs KDE). windows don't have title bars, things are very rounded, not very configurable, heavily mac inspired
tiling window managers
these aren't desktop environments, but sit more in the middle, they manage windows. best to watch a video about tiling window managers. they are very geeky and perfect if you love using nothing but your keyboard
I see a lot of Framework recommendations, and I had the 12th gen Framework for around a year running Fedora. I faced a bunch of excessive power use issues, and had to add some kernel flags just to get maybe 4 hours of battery life. The device is notoriously repairable, but the one thing that conked out on me was actually the mainboard, which was like the price of a new device. Support spent two weeks trying to find out if it was anything else before sending me a replacement mainboard.
My friend recently god a Zenbook 14 OLED with the same processor. The entire device was $200 cheaper lightly used than the Frameworks mainboard alone, and the only issue is the speakers don't work. That being said, he gets almost double my battery life, and an OLED screen on top of it all. Plus more ports; even with Framework's modular add-in cards I don't feel it is as flexible a system as having >4 useful ports.
My time with the Framework was great, but I wouldn't recommend it. Getting something secondhand is an environmentally conscious option, and you can get great stuff secondhand.