The species you choose to play in D&D is a reflection of your interests. Whether you think this species looks cool and you're interested in playing it, or you're there to roleplay something unique, or you just want to min-max a character till it's overpowered that's up to you.
In the end, all the characters you play in D&D will have their strengths and weaknesses. What the best specie is will depend a great deal on the circumstances, as some campaign settings may undermine a species strength rendering it useless. So this list focuses on species that have abilities that are effective regardless of setting, or that are so good even if the setting is not optimal they're worth taking.
10 Lizardfolk
These are really quite the best well-rounded species you can play in D&D right now. They have a variety of awesome features that come with them, but they have the ability to make their own weapons and armour from the natural environment that stacks with their natural armour.
They then have limited aquatics, which can only help and rarely hinders anyone. Their bite is 1d6+Str, making it functionally the highest unarmed attack for the playable creatures out there. This bite also gives them temporary HP once per long rest. They have utility in spades and are not really limited by setting, except for charisma and polite society for the most part.
9 Half-Elf
Benefiting from both their human and elven heritage these individuals get a +2 to Cha which makes them fantastic as Cha casters. They also get a +1 in stat proficiency of their choice, which is not bad, but it's their fey ancestry they get from their eleven half which makes them fantastic.
They get advantage on saving throws against the charm effect, and can't be put to sleep by magic. Darkvision never hurts as well, and their Skill Versatility gives them an extra two skill proficiencies which probably comes from their human heritage. These make for some great stats for a caster that can handle a variety of settings.
8 Elf
Much for the same reason that the Half-elf makes the list, the Elf follows up behind due to the variety of subraces and fey ancestry. The sub-species available to them can make them pretty useful in a variety of settings, the Drow for underground campaigns, forest elves for foresty settings, etc.
The Shadar and Eladrin get special attention here though, as they both get a teleport as part of their specie's traits. Anything that gives you a teleport is great, whats greater is depending on the Eladrins chosen season it can do magical effects to enemies. However, it's all the variations of elves that are available to choose from and which gives them the spot on the list.
7 Aarakocra
These bird people are on the list as they get a major ability simply for having wings, they can fly in light and medium armour. This is puts on the list alone, having the ability to cast a 3rd Level spell at will is invaluable. In D&D editions past like 3.5 and alike fly could render certain threats useless and it still can even now.
Besides a focus on Dex there is little else to say about the Arokocra other than their claws. These give them a 1d4 unarmed slashing damage attack, free knives essentially. These creatures are really only hampered by underground adventures, and only when there isn't a cavern with not enough room to fly in.
6 Changeling
These guys are not allowed in adventurers league currently, that should say something about them. As an action, they can take on the appearance and form of a another humanoid creature which they choose. They can even copy the likeness of characters they have never met.
This coupled with the natural +2 to Cha and two skill proficiencies chosen from insight, deception, persuasion, or intimidation give these creatures amazing stealth and infiltration capabilities. The changeling is a one-trick pony fundamentally, but that one trick they do so well it earns them a place on the list as this sort of trick is always useful.
5 Yuan-Ti Pure Blood
Magic resistance is amazing, it gives you an advantage on saving throws against magic and magical effects. This along with some innate magical effects give the Yuan-Ti Pure Blood a spot on the list. The number of times your characters are likely to be subject to magical effects in a D&D game are numerous.
Being able to increase your chance of avoiding getting caught in one is invaluable. If it is magic and has a saving throw involved then you get this benefit. The Yuan-Ti Pure Blood getting to befriend and charm snakes along with a free poison spray cantrip AND Darkvision aren't bad either.
4 Dwarf
The Dueregar and Mountain Dwarf specifically get the dwarves on this list. The Deuregar though having sunlight sensitivity, a big drawback, benefit from some really powerful spells later on like enlarge and invisibility simply for free. The Dureugar also have magic resistance to illusions or being charmed or paralyzed.
The Mountain Dwarfs are just stat block beasts, +2 Str and +2 Con make them some of the best-suited creatures for combat. Coupled with their dwarven resilience and natural training in some martial weapons and medium armour for free make them powerful and straightforward.
3 Shifter
The shifter gains a variety of benefits based on their background, but they are tied to their major ability which is to transform into a more animalistic version of themselves as a bonus action. They can take on traits of a specified animal they identify with. This gives the shifter temporary HP equal to their level plus their Con modifier.
Getting temporary HP on a shift, getting a 1d6+Str bite attack, increased movement speed, or never having to worry about any enemy getting advantage against you on their roles are amazing. You can only choose one of these bonuses based on the sub-species of shifter you choose though.
2 Tiefling
The Tiefling is a not all that interesting on its own, but with the variety of subspecies now available to it they have become far more interesting and powerful. These are generally altering the +1 stat modifier you receive as part of the subspecies along with the general +2 Cha modifier.
The Tieflings now based on their background can get brand new cantrips and spells for free as they level up. This gives them the variety they lacked beforehand and can really round out a class.
1 Tortle
The Tortle has an incredibly high Natural Armour of 17 and the ability to retreat inside their shells for an extra +4 to round them out to an AC of 21. They get claws that do 1d4 damage and are partially aquatic creatures giving them some versatility.
The Tortle on its own isn't a very good species as they don't gain the benefits of wearing armour, but they make this list as there are classes that get benefits only IF they are unarmoured. A Tortle monk or barbarian essentially get the Tortle to the list as they are strong and versatile.