The best replacement for 5x7 is 4x6.

The best alternatives to 5x7 are rated as following:
★★★★★  4x6
★★★★  8x10
★★★★  6x8
★★★  6.5 speakers
★★  6x9
★★  5.25
★★  4x6 photo
★★  4x5
★★  5.25 speakers
★  6x8 speakers
  4x6 prints
  8x10 photo

Your alternative for 5x7 is not listed? Suggest!
Speaking about 5x7, one probably shouldn't forget about 8x10 picture frame.

Other search terms related to 5x7 and their ratings are:
★★★★★ 8x10 picture frame
You have in mind a companion for 5x7 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of 5x7 in all years. Click on graph for more.
5x7
4x6
8x10