I just found a nice summary to help you find out what could be an optimal Windows Lumia phone for you, since the overwhelming amount of numbers could be confusing:
| 5x | Cheap phones |
| 6x, 7x | Midrange phones |
| 8x | Cheaper flagship phones |
| 9x | Flagship phones |
| 10x | 41mp phones |
| 13x | Cheaper phablets |
| 15x | Flagship phablets |
| 25x | Tablets |