well, to go off topic i will have to say my ak-47, simply because i can make a inacurrate conversion of a drugonov on it (not aim, just looks). but my m4 is the gen2 model so it performs maybe a little better than my ak and has far more upgrades availible.
also if you are living anywere cold, i would definatley shy away from the kar98, s your gas consumption/pressure will suffer horendously. if you are really good, you may want to take a VSR-10's guts aand put them into a hommade wooden body of a KAR98.