In 2015, LEGO released 10 Classic sets across 4 subthemes, all of these sets have been retired. Subthemes for that year included Baseplates, Creative Box, Creative Building, and Miscellaneous. For that year, the total price of all retail sets cost $268, today those sets are valued around $525.
Most valuable 2015 LEGO Classic set
10697 XXXL Box $349.99
Most owned 2015 Classic set
10696 Medium Creative Brick Box
10 sets

10692 Creative Bricks

Theme / Subtheme Classic / Creative Building
Year 2015
Pieces 221
Availability Retired
10692 LEGO Creative Bricks
Retail $16.99
Value $25.00
Growth  +47.1%
Annual growth 7.6%

10693 Creative Supplement

Theme / Subtheme Classic / Creative Building
Year 2015
Pieces 303
Availability Retired
10693 LEGO Creative Supplement
Retail $19.99
Value $25.47
Growth  +27.4%
Annual growth 3.2%

10694 Creative Supplement Bright

Theme / Subtheme Classic / Creative Building
Year 2015
Pieces 303
Availability Retired
10694 LEGO Creative Supplement Bright
Retail $19.99
Value $25.90
Growth  +29.6%
Annual growth 3.0%

10695 Creative Building Box

Theme / Subtheme Classic / Creative Building
Year 2015
Pieces 580
Availability Retired
10695 LEGO Creative Building Box
Retail $24.99
Value $39.78
Growth  +59.2%
Annual growth 6.3%

10696 Medium Creative Brick Box

Theme / Subtheme Classic / Creative Box
Year 2015
Pieces 484
Availability Retired
10696 LEGO Creative Box Medium Creative Brick Box
Retail $34.99
Value ~$34.99

10697 XXXL Box

Theme / Subtheme Classic / Miscellaneous
Year 2015
Pieces 1,500
Availability Retired
10697 LEGO XXXL Box
Retail $59.99
Value $349.99
Growth  +483.4%
Annual growth 11.5%

10698 Large Creative Brick Box

Theme / Subtheme Classic / Creative Box
Year 2015
Pieces 790
Availability Retired
10698 LEGO Creative Box Large Creative Brick Box
Retail $59.99
Value ~$59.99

10699 32x32 Sand Baseplate

Theme / Subtheme Classic / Baseplates
Year 2015
Pieces 1
Availability Retired
10699 LEGO 32x32 Sand Baseplate
Retail $7.99
Value $28.00
Growth  +250.4%
Annual growth 7.4%

10700 32x32 Green Baseplate

Theme / Subtheme Classic / Baseplates
Year 2015
Pieces 1
Availability Retired
10700 LEGO 32x32 Green Baseplate
Retail $7.99
Value $15.34
Growth  +92.0%
Annual growth 9.0%

10701 48x48 Grey Baseplate

Theme / Subtheme Classic / Baseplates
Year 2015
Pieces 1
Availability Retired
10701 LEGO 48x48 Grey Baseplate
Retail $14.99
Value $15.96
Growth  +6.5%
Annual growth 1.1%