Intel i3, i5, i7 (or i9)
Do not get Celeron or Pentium
Check the performance on www.passmark.com. Highest rating is 20,000 which is a Xeon. In 2018 you'll want a minimum of 3,000.
4GB RAM minimum
- SSD is 10x faster than HDD. Also consider NVMe rather than SCSI
- WiFi: ac compatible, 4x MIMO is better
- Bluetooth 5.1 is the latest
- Storage: Windows needs at least 50GB to upgrade on its own. Some games can be 200GB. Office takes 10GB.
Dell, HP, Lenovo, Toshiba, Asus, Acer, in that order
For gaming laptops: Razer, Alienware, Zoostorm
Amazon, eBuyer, Overclockers, John Lewis, Currys/PC World