Ekko is a bursty melee who's main gimick is diving into the enemy team to try and kill a squishy, and then using your ult to get back out before you die. The skill with playing Ekko is knowing just HOW long to hold your ult before you bounce back out. Hold it too long, and you risk dying. Hold it for not long enough, and you basically just jumped in and didn't do nearly enough with your damage before bouncing out.
Sion is a tank with telegraphed abilities that HIGHLY reward a player who can consistently find ways to tag enemies with them. Yes, people say that playing Sion runs you the risk of being outplayed. But that risk exsts with every champion. Sion is not picked well into champions like Fiora who can easily dodge or parry your Q for a stun. However, a good deal of his matchups he ends up bullying when you get good at consistently landing E.
Sion and Ekko are also great roamers. With Sion, you can back, walk down bot lane and then ult for a free gank, teleporting back to lane once you finish up helping bot take first tower. With Ekko, you can surprise people with your W from the bush with its huge range, and most of the time force flash very easily when they realize that getting away from danger means walking through your W.
I think you might like both of them. Of course Sion is not as expensive as Ekko is in the Blue Essence department, so he might be a good place to start