I'm confused in selecting a desktop?

Whatever you choose make sure it has an SSD plus a hard drive for storage. SSDs are fast but larger ones are very expensive. So you use the SSD for the OS and programs and you can store all your data, photos, videos, music etc on the hard drive.

You can be fairly sure that the manufacturers know more about costing a PC than you do. So it is unlikely that you can do better than spending as much as you can to get as much power as you can afford.