In some metroidvanias, most famously the Igavanias (including Bloodstained: Ritual of the Night), you can earn experience from enemies and level up if you earn enough. Hence, you can become stronger just by killing the same enemies over and over (though a couple of the earlier Igavanias (Symphony of the Night and Harmony of Dissonance) made it so that enemies eventually only award 1 XP if your level is high enough). Dust: An Elysian Tail and Timespinner are other examples of games that use this mechanic. (There's also the possibility of non-XP systems that reward fighting enemies, but I'm not aware of any metroidvania that uses such systems in place of a level/XP system.)

In other metroidvanias, most notably the Metroid games, though I could also mention Hollow Knight here, you don't have a growth system of this type. To get stronger, you need to explore the game world and find upgrades hidden in it. This means that you can't over-level in the conventional sense, but it means that it might be better to avoid enemies rather than kill them (though killed enemies can drop health/ammo refills in some games). Another example of a game that takes this approach is Guacamelee!

So, which of these different styles of metroidvania do you prefer?

I really like it if you have level-ups like in Igavanias, particularly because you level up fairly naturally in them. I don't think i ever had to grind in any of them so there is no tedium, but you becoming noticeably stronger is an additional motivation for me to explore the map.

Yes I love it! I actually like a combination of both, where you level up and you get new skills/upgrades as you explore, and you additionally get abilities from bosses or specific places that allow you to explore further/unlock previous paths that you couldn't access. Castlevania metroidvanias are a great example of this, in many of them you can actually farm the enemies to get cool drops and level up, but if you're good enough or don't want to/need to, you can just beat the enemies with your skill, so those who enjoy farming and overlevelling/collecting can do it, and those who want to can just run through the game while defeating enemies with pure skill, even if underlevelled.

Doesn't matter that much to me but I think I prefer power ups placed behind puzzle or combat challenges, and being able to avoid combat when I want to. What does matter is if the (movement-focused) abilities gained are fun to use.

Both systems can be cheesed and benefit from some dynamic difficulty balancing.

Guacamelee isn't that different from leveling; you generally beat enemies to gain the gold which you trade in for upgrades at the save points.

Hello dtgreene!

My favourite Metroidvania-style games tend more to the formular of the original "Metroid" (on the NES) or "Super Metroid" (on the SNES), and do not feature XP-level mechanics. From the Castlevania series I actually do prefer the more action-oriented "Super Castlevania" (on the SNES) and "Rondo of Blood" (on the PCengine).

Generally speaking, I did enjoy "Symphony of the Night" (on the PS1) and the Gameboy Advance follow-ups. What I disliked in them was the random loot/item drop and the XP-level requirements associated with some of the equipment.

Yes, you can skip the "farming" of better item drops in "Symphony of the Night" & co., but once knowing of the better items available per random drop it incites me to keep farming enemies for at least one or a couple of those more valuable items. And it gets more challenging to resist this urge.
Stat-based or XP-level-based requirements for item/equipment usage is something I do not like even in roleplaying games or action games with roleplaying elements. Although being some of my favourites, strong offenders in this regard are the games of the "Gothic" series, where you finally gathered the LP's (learning points) to learn the new weapon skill for a weapon you collected eons ago, only to find that you need many more LP's to increase your corresponding status value, as well.

Since, I played the first Zelda game (on the NES) before I experienced Metroid, I consider the Metroid games more as 2D side-scrolling, science-fiction version of the same formular of item-based area progression and finding of hidden items!
Furthermore, I am looking more for the discoveries of exploration in those type of games. This can be fun even without any item-based progression system, as "VVVVVV" (The Letter V Six Times) and other individual games do demonstrate.

Finding an hidden item, whether actually hidden or just in a not so easily accessible room, is so much more satisfying to me when I finally find the item or get access to its locked/hidden room!
Because this way of item-based progression gives me the illusion that I myself achieved to do so, instead of random chance for a loot drop or "grinding" for XP or items (both just an exercise in endurance/persistence).

Kind regards,
foxgog

[Edit: After some more consideration, I would like to add that for me the lack of a XP-level system stresses further the survival theme in an harsh and isolated environment of the Metroid-like Metroidvanias, while the XP-gain nurishes more to the power fantasy of getting "stronger".]

I also prefer Metroidvanias with leveling up. That motivates you to fight instead of just running away from enemies.

I don't remember any of this in any of the GBA/DS Castlevanias, or in Symphony of the Night. The closest I can think of is abilities costing more MP than you have at full MP, and I only remember this being an issue for SotN, when certain abilities that you could theoretically use from the start (like Soul Steal) cost more MP than you have, making them unusable.

(Related note about Circle of the Moon: There's a glitch that allows you to use magic without the required cards. It turns out that lack of MP isn't a problem, as with this glitch you only need a minimum of 0 MP to use the associated spell. You still have to pay the cost, and it can (and will) cause your MP to go negative, but that still allows you to cast the spell anyway. You *do* need to get the first couple of cards to do this glitch, but they drop easily so that's only a problem on Fighter mode (where they never drop), but Fighter mode is really easy anyway.)

Hello dtgreene!

Indeed, you are right. That MP-requirement was what I had in mind.

Sorry, I did not made it clear in my earlier post, especially since I worded it only with item usage, and additionally mentioned only the Gothic series as negative example.

Kind regards,
foxgog