Delta squad for offense Riot Sheild Squad for defense.

Riot Shield Squad all the way Delta team always dies before the round is up :[

Neither since both units tend to run infront of my Sentries. :C

Actually I find the delta squad quite useful in maps like dome where I will hold down one position and not have to move but the riot shield squad is nice on maps like interchange where there isn't much cover. My strategy is to hold down a sector (like the weapon area in Dome) and survive until they call in helicopters, juggernauts, ect. It works pretty well until later rounds but by then your best bet is to buy riot squad and put up some sentries but the only reason not to use riot and sentries first is because they are expensive and wasting your money can really hurt you in the long run.