I recommend Fizz. He can build tank and still kill enemies. But you need to be ahead of your lane opponent to be effective late game.
I also recommend Ekko, but you need another 100 RP to buy this champion (or 6300 IP). He really fits your play style. And this boy has a reset button ( Chronobreak) to escape/outplay.
Lastly, I recommend Poppy. She is usually built as tank but can wreck opponents if you played her correctly.
But again, you should be frugal at spending RP. You should spend those for buying rune pages and skins, not champions. But it's all up to you.
I am now using Le Blanc but i still haven't mained her.I'm planning to buy a champion that is fun to play and a champ that can kill guys late game and at the same time be a tank.Most likely i like assasins.
Just save those RP for a while.
I also recommend
Lastly, I recommend
But again, you should be frugal at spending RP. You should spend those for buying rune pages and skins, not champions. But it's all up to you.
What is your main role? What is your playstyle?
RP only