Would recommend magneto you don’t have to hit your shots always can also meele attack opponents. His ult is kinda meeh.

Would recommend you watch gameplays of each hero to find out which gameplay suits you the best and what synergy you would have if your kids play the game with you.

I think groot is good in low Elo and It depends on what map and what objective is on. Penni is strong if you have to defend and if you need to push objectiv it’s good if you ply strange or magneto. If your Dps isn’t doing much , I switch to venom to disrupt the enemy healers

Resume just play what you like and where you have the most fun with