SGCs, in my opinion, are the easiest of the 3. A small flat-head screwdriver will get it started. Put it along the seams and carefully twist. Continue that till you get a bite, then it'll start cracking the seal. Continue along the seam till a larger flat-head will work. When you get good (have done enough) it'll only take like 30 seconds. Your first time will take like forever cuz u're worried about slipping and either stabbing yourself with the screwdriver or damaging the card or just not knowing what u're doing. Just like anything else
Good luck!