If you buy CONNECTORS, you need these: 50x ATX crimp terminals FEMALE Minifit-Jr for ATX, PCI-E and EPS, made for 16 AWG and 15 AWG (1.50mm²).
FEMALE crimp terminals are always used for CONNECTORS.
The difference to the standard Minifit-Jr AWG (17-18) FEMALE version can be seen in the second photo. The only difference is the length of the conductor "wings", which wrap around the conductor of the wire when crimped. Both size versions are 100% compatible with all connectors and mating terminals.