your big hitters out of neutral (best reward) are DED, dtilt, dash attack, and grab. next in line you have moves like ftilt, jab, nair, and fair, which are generally going to be more defensive for you in neutral, and wont yield as much reward (fair can combo but you wont get anywhere trying to use it as an approach on a grounded opponent; youll just get CCed).
out of the ones ive mentioned, try mixing it up, especially by trying to land dtilt, which is arguably your best set up, and one of your safest moves on a shielded opponent (besides grab obviously). between dtilt and DED, youve got two moves that set up greatly, can be used safely on shielded opponents (when used properly), and offer differing coverage. DED covers the airspace above and in front of you very well, while dtilt offers a good, long range poke to the ground that can be used with CCing. when to use which move depends on where youre looking to cover space, and the dynamics of your opponents approach game. both however, can be beaten by CCing, which is where you can mix in DDs, grabs, and sometimes even a surprise DACUS.
the main need for roy to carefully choose his moves from neutral is the fact that everything he has besides grab and upsmash can be CCed, and DACUS isnt exactly a reliable approach when used too often, and gets beaten too easily by shields. i can see how its easy for you to get used to DED if your opponent doesnt CC, but when they do, it really forces you to weigh your other options. if CCing werent in the game, DED would turn into one of the most reliable approach moves in the game, as it racks damage, kills, and can combat shielding opponents.