Desktop PC. Assuming you want something to use for trading which doesn't limit you, I went for a gaming PC, 64 GB RAM, SSD and quiet operation (can adjust fans with buttons on the case). There were some trouble with gfx card which had to be replaced, but it's been smooth operations since then. Running Linux, so BSOD or forced upgrade-cycles are moot. The OS and much of the software is free, and can always be reinstalled. Can recommend Linux Mint to get started quickly.
This works for everything for me, but I'm not daytrading and only playing longer term trades. So while I'm waiting for analysis to complete, I often play online games on Steam, to chill out.
Of course your needs might be different, but today, there's no need to switch desktop PCs until after 5-10 years, if you're lucky. If HDD fails, just buy a new SSD, since of course you have proper backups. Everything becomes cheaper in time. You'll need to blow off dust every few years and keep an eye on the fans, but other than that, there's no reason a real PC can't last 10-20 years, though you might get unlucky and need a replacement before that.
If you buy proprietary garbage, of course, it will stop working and limit you. However, besides HDD, fans, powersupply and proprietary software, PCs are actually pretty resilient. Buying new PCs today doesn't really buy you much in terms of upgraded performance, and it makes sense to limit waste.