I love Metroidvania games and it's been such a blessing that they have been going strong in the last few years because for a while it seemed like a dead genre.

Some of my favorites are:

Super Metroid
Castlevania: Symphony of the Night
Guacamelee 1 & 2
Hollow Knight
Ori and the Blind Forest
Axiom Verge

Hollow Knight is on my ”to play” list. 

Oh I also wanted to add that although I love the Prime series to death, I don't consider any 3D game to be in the Metroidvania genre. It has to be 2D.

I don’t want to offend anyone but I hated the original Metroid, Metroid zero mission is amazing though, better than fusion and almost as good as super.
To me symphony of the night is still the best, but today we have many great metroidvanias, one game that doesn’t get enough attention is shatae and the pirates curse, that game is really fun and does metroidvanias in it’s own way.

My very first Metroidvania was Blaster Master. And then maybe Faxanadu (if it can be counted...maybe not). I didn't play the original Metroid until a number of years later.

But Jesus H Christ, I love the Metroidvania genre. It scratches my gaming itch so perfectly every time. Oh, and I do consider the first two Prime games to be Metroidvanias. Sure, it's 3D, but the underlying exploration and progression is classic Metroidvania. The third game is a little different since it's got multiple planets.

Yeah it’s just a great formula. Some mechanics and gameplay loops just lend themselves to better experiences and the Metroidvania formula is a great example of that.

I’ve actually been working on a top 10 Metroidvania games—which will probably be top 25 when it’s all said and done. There’s been an explosion in the sub-genre lately, with 2018 being a banner year.

my first metroidvania was fusion. it might be blasphemy but its still my favorite metroid, although i thought zero mission was pretty amazing too. the new generation of metroidvanias has been top tier though. ori and the blind forest, guacamelee 1 & 2, hollow knight, axiom verge, and even teslagrad (which is kinda linear) were all great games that i replay whenever i don't know what to do with life

Can't wait to see that when it's finished.  Yeah, 2018 certainly brought me quite a backlog that I'll probably never get to.  That's why I love these lists so I know which to work on first.

Hopefully Bloodstained will be one of the genre´s best games, with Iga behind it, hope he hasn´t lost his touch.

If you are stuck on Soul Master, it is possible to progress the game and finish an any% run without beating him, but it involves buying the 1800 geo lantern now (which you would have needed to do later on anyways).