If you're limiting this to Metroid-style...
Start with Symphony of the Night (SotN). Factoring in everything, it's still the best, honestly.
If you like SotN, you will probably want to transition into Aria of Sorrow, as it's the closest game overall to SotN.
From here, you have choices to make. If you want "more of the same," go with Aria of Sorrow's direct sequel, Dawn of Sorrow. If you want something similar but different, I'd go with Harmony of Dissonance (HoD) or Circle of the Moon (CotM). I just replayed HoD, and it was a lot better than I remembered it being. It's a cross between SotN and Circle of the Moon. Its map can be very confusing and frustrating, though. Circle of the Moon is more of a cross between the original style of Castlevania and SotN, so it's quite challenging.
I unfortunately cannot personally speak for Order of Ecclesia, but I've heard good things about it.
As for Portrait of Ruin...it's a really mixed bag. It's "fresher" than some of the Metroidvanias with its gameplay, but its maps are more tedious and repetitive overall.
Again, I skipped Order of Ecclesia (I was burned out on Metroidvania); but for me, SotN, CotM, HoD, and AoS were the most worth playing. DoS and PoR felt like "leftovers" in one way or another.
If you want games that are transitional Metroidvanias (meaning, they were precursors to SotN, but started to add exploration and RPG elements), you might try out Castlevania II: Simon's Quest and Castlevania: Rondo of Blood.
While even less Metroidvania, the two underrated albeit rough-around-the-edges N64 titles (Castlevania 64 and Castlevania: Legacy of Darkness) also have questing/RPG elements to an extent. The two PS2 games, Lament of Innocence and Curse of Darkness do also, but I felt they weren't as good 3D efforts overall as the N64 titles. It depends on what you're looking for.
Bottom line: If you want Metroid-style, try SotN first.