CCM flyback or DCM flyback
Battery charging is usually low power and suits DCM better for size and efficiency. Whereas high current 100W converters reducing the current swing is advantageous with CCM to avoid saturation.
DCM advantages          DCM disadvantages
Lower primary L needed  Higher peak primary current
L sets the max %d.c.    Higher peak rectifier current
Smaller Xfmr possible   Increased input capacitance
No diode reverse losses Increased output capacitance
min FET turn-on losses  Potentially increased EMI
No right half-plane zero Wider duty-cycle needed than CCM
Optimal for low Pout    Increased bandwidth variation

DCM flyback designs have both advantages and drawbacks relative to CCM designs.