Other Metroidvania beside Igavania

Salt and Sanctuary. It's like Igavania's SotN meets Dark Souls.
Leveling is certainly a thing in that. I also suggest an odd ball... 

El Shaddai: Ascension of the Metatron (not really any leveling here and few igafania scenes, but worth a glance for the mythos).

Igavania-like games (some aspects, but not all):

Shantae
Shovel Knight
Guacamelee!

[reserved for more suggestions]

For readability's sake I'll present an ordered list.

Aquaria (PC)
more metroid than vania. You play as a young, water breathing humanoid that utilizes a force called the verse, by singing, to alter herself and the world around her. The majority of the game is set beneath the ocean and the story centralizes on searching for a sense of belonging while unearthing a mystery.

Scurge: Hive (DS / GBA)
The protagonist, Jenosa, has been tasked with hunting an alien parasite of mythical capabilities. It's a constant battle against time and the environment as the parasite infects everything, including Jenosa. It can best be summarized as a metroidvania lite set in a sci-fi horror theme.

You Have to Win the Game (PC)
A charming little title that can take less than a few hours to beat. It's a retro looking platformer with character upgrades some puzzles. There are additional game modes that change the layout of the world as well. There's no RPG elements or even gear to swap out so the vania is quite lacking.

^ lol, I've played that game. It's clearly trying to copy Castlevania, but it wasn't terrible.

Anyway, it has come up several times in the past how Dark Souls/Bloodborne could be considered a modern 3D Castlevania game/Metroidvania. Looking back on my previous points, I think I would have to agree on the basis that they DO have both parts that I was commenting on earlier, specifically a game like Dark Souls 1:

Completely interconnected world with shortcuts that open up with exploration/acquisition of items
Emphasis on item collection and management, to the point that even the story itself is told largely through them
Powers/abilities also acquired through things found, drops and equipment
Similar UI resource bars, setting, enemies

I used to see people say this and kind of write it off as a surface level comparison until I thought about it more. I think that this probably subconsciously led me to enjoy these games more.

In case you're curious, here are some differences looking at other Souls games, the ones that to me seem less 'vania overall, but still have elements of it:

Demon's Souls:
- More level-based, but still interconnected within levels
- The most hub/town based, which sometimes is a 'vania thing, but not usually to that extent
+ MP bar

Dark Souls 2:
- Not as interconnected, more strung linearly exploration-wise, but teleports available to every area immediately
= Various convenience/ease of use touches compared to earlier games

Bloodborne:
- Less emphasis on equipment, magic and attack variety, more of a faster action game than an RPG
- Less variance in playstyles because of this
+ Closest in setting/time period overall, as well as enemies
= Also very much like Demon's Souls in being interconnected, but also strongly hub and level-based, however, unlike Demon's, the areas are all accessible between each other in some way without use of the hub

Dark Souls 3:
- Demon's/Bloodborne style hub, but with Dark 2's method of traversing levels (can teleport to all areas)
+ Less emphasis on being undead/hollow (your character more often looks like a human)

Those are pretty much my thoughts. If you haven't played any of them, I would just recommend starting anywhere along the line with whichever one sounds good to you, since they're mostly not all that related. If you go for Dark Souls 2, get Scholar of the First Sin.

They actually have a Ninja Turtles game that is as close as any other game that tends to get mentioned. It's called Danger of the Ooze. You get upgrades to open doors, double jump, climbing, experience to level up some abilities. The combat is a little stiff, and the game is pretty short (there's a one hour speedrun trophy/achievement), but other than that it's pretty good.

I think Apotheon is a Metroidvania game. I heard good things about it.

I've played Axiom Verge (which was REALLY good, kinda lost it when I heard it was coming to Wii U), but besides that not too much oddly enough (besides literal Metroid or Castlevania games I guess).
...Does Megaman ZX count? (Prolly not)

Muramasa Rebirth isn't any closer than the other games that people tend to list, but I just wanted to mention that it really is a great game. Easily one of my favorite games from the past 4-5 years. Last year after the Kickstarter was revealed, I wondered if IGA went to Vanillaware with his pitch. I'd love to see what they could create together. Also on the topic, Odin Sphere Leifthrasir is being released today, and I'm eager to play it.

To add my own request.. Salt and Sanctuary, which makes the perfect fusion out of Iga.. pardon Metroidvania x Souls =)

I liked the Strider remake and Aquaria.