LATCH vs. seatbelt

JJ3813

I broke out our car's owners manual and discovered we cannot use the LATCH system in the center of our back seat. Would it be better to use:

LATCH on drivers side

LATCH on passenger side

Seatbelt in the center seat?

 And is it the same for infant carriers and RF-FF convertibles? 

Sorry if this is a dumb question...this is our first car seat experience so we're just trying to figure it all out

 Thanks