They were both good, 4 got really hurt due to terrible pacing and the start of the game being really dull (dunno bout you but the robot enemies are boring as fuck).
5 was good, I liked the choice to tackle small skirmishes as you like, just that the game world was too big and not really enough reason for it it be so. They could have had user selected random sections but without the bland romp to get there.
If the Coalition will continue working on Gears' properties I really hope they will read the books and include something from the
Pesanga, that whole part of the Gears universe seems missed and could open up the combat quite a bit..