Dupes are fine, but 3* and 4* pulls in FKG are useless. Do you feel good when you spend 5 bucks and get a 3*? However, there are no useless 3* or 4* pulls in the BGR 1$ plat gacha, all of them can be used to rank up and eventually get UR on your preferred units. In addition, you get 5 times as many of these units for the price, so even though you need a lot to UR, none of them are useless and you get a lot more of them.
I like their gacha system design better than FKG's. However, I like that FKG has H-Scenes on all its girls, and not just a few unique ones.
I also like how BGR's combat system is not so RNG reliant to get what you need, unlike FKG where 3-starring tricky maps involves running them dozens of times until RNG finally gives it to you.