Honestly both also can lah but if i were u id go Sengkang green, more established and got better rep in the area. Fern green is newer so less track record but tbh the PSLE results not bad also, got kids go RI and NYGH. Just note that Sengkang Green is quite competitive to get in during P1 reg, so depends on which phase u registering under and how close u stay. Fern Green easier to get in and got quite good STEM programme if ur kid into that kinda thing. At the end of the day both should be fine 😊