If your building a warbird they tend to need nose weight so Zenoah shines here, but tends to be more expensive. If your doing sport or 3D where weight is a concern and yer on a budget then DL, spe, crrc... The spe engines are awesome but their ignitions are complete garbage and an instant repacement with an rcxl is needed. DL is great and their 50 and 100 are interchangable with DA parts ie mufflers etc.. The DL30 would be a good cheaper choice for the Balsa USA 1/4 scale planes. My DL50 has ran great right out of the box. With sport and 3d and cost is not an issue then go with DA or 3W, they rock!