The start of league is probably the hardest for the simple fact that there is so much toxic players. However, once you've reached level 30 I would highly suggest going into rank and playing even if you're new but play champs you're able to carry with because at times it'll be the case of you leading your team to a win. I rather play ranked than normals because in rank you're playing with people trying to win and people based on your skill and not people afking or inting because they're tilted. However, if you want to try a new champ I suggest doing it in normals since your team will tilt.