I agree that build to order is the way if you prefer a desktop, eg need a big screen for photo editing or for gaming.
For general work I use laptops, bit hard to take a desktop with you. My laptops last longer than my appetite for a change so I end up with oldies, but still work ok.
Check out this site for build to order, good prices, and also build quality
Quoting a build as low as: $273.00 Availability: Build to Order PCs usually ships in 3 to 7 days
EG
MediaPro M6000 Intel Custom Built Desktop PC SKU: DSPC9600 Price as configured below: $795.00 • ASUS P8H61-MX R2.0 LGA1155 DDR3 uATX Motherboard OEM • Intel Core i5-3470 Quad Core 3.2GHz 6Mb 22nm LGA1155 CPU • Kingston ValueRam 8GB Kit 2x4GB 1600MHz DDR3 RAM • Gigabyte GZ-M3 Black uATX mATX Mini Tower Case • 350W ATX Power Supply • Intel® HD Graphics Full HD 1080P • 1Tb Green SATA-3 6Gb/s Hard Disk • 24x Dual Layer SATA DVD Burner Writer • ASUS VS247H 24" 23.6" Full HD 5ms HDMI DVI LED Monitor • Gigabyte GK-KM6150 Elegant Multimedia USB Keyboard & Mouse • Microsoft Windows 8 64-bit English OEM OEI OS DVD