Why would someone want to play a eldritch knight

[Sir cryosin]

I sure my character is going to die soon and starting to roll up a new one I was thinking about a EK that is constantly insulting monsters to try and get them to come in attack him. But I'm afraid how poorly the DK archetype is compared to others. So I would like all of you fine people to sell me on playing a EK. Or sell me on some other spell blade tank.

[mer.c]

You're right that creatures may not want to attack you since EKs are so durable and don't have the highest DPR out there. But you can always grab the Sentinel feat to punish creatures who want to ignore you. Also, along with advantage on Concentration, War Caster lets you cast Booming Blade as an attack of opportunity to lock an opponent down. War Magic even lets you BB plus make one attack with your Attack action, so until you get your third attack, you don't even lose damage off attacking with BB. That plus Sentinel lets you lock down two creatures per turn if you hit with both.

As for specific builds, there are some great EK guides in the stickied Notable Threads topic here in the 5e forums.

Actually, if you really want to lock things down hard, I wonder if you could make a grappler EK. It seems like it should be feasible.

[Talamare]

EK is good or not depending on if you have SCAG spells or not

[MrStabby]

Well the fighter chassis is a great basis, at least for the early levels. You are a caster who can make good concentration saves, have solid armour if you want it, you get action surge, multiple attacks, you can support more styles than most through all the ASIs feeding you feats. Fighter can multiclass well as you need good Dex or Str, not both.

Eldritch knight abilities are mixed - and tend to benefit from multiclassing. The spells slots are limited, and can seem narrow but cantrips if used wisely can add a lot of depth to a character. Shield makes EK one of the best tanks out there.

The ability to make an attack following a cantrip is great if you build a character around it (say with rogue so your 1 attack can carry a lot of damage or if you can stick a rider on the ability).

The ability to give disadvantage on saves is great, but again you really need to build around it to get the most from it. Sorcerer for quickened spells is good to get more benefit, but 5 levels of cleric for spirit guardians or similar can be solid as well.

My case that EK is good, is that it is good for some things but you should have a specific idea.

[Final Hyena]

I managed to convince a DM to let me use a THW and still cast spells as I can just let go with one hand, it was a good character but hardly broken.

[Tenmujiin]

I managed to convince a DM to let me use a THW and still cast spells as I can just let go with one hand, it was a good character but hardly broken.

Fairly sure that is the standard interpretation of the rules if not RAW.

[coredump]

A fighter that gets shield spell...

[CantigThimble]

A fighter that gets shield spell...

And blur. And magic weapon. (if your party doesn't have a better way to overcome that damage resistance) And absorb elements. And hold person. Battlemasters and Champions deal more damage and have more combat utility but EKs get so many more options. Not to mention the fact that they're still fighters.

[Mors]

With GWM, SKAG cantrips, Haste and their 7th lvl ability they can also deal considerable DPR, in addition to their spellcasting utility and defences. It is really a great all-round archetype, it just needs some lvls to get going in contrary with Battlemaster and Champion to a lesser extent. Make no mistake though, it does surpass them once you have all the pieces set in place.

[Lines]

Fighter's a great chassis, especially early. Problem is it starts to flag a little later on, you go from getting a lot of good stuff in terms of dealing and taking damage to getting some ok abilities to further take and deal damage while other classes are getting the same thing but also expanding in breadth, getting abilities that make them good at new things. Champion is boring and crap at all levels, increasing your combat ability by a slight amount early and just giving you more (underwhelming) combat ability late while battlemaster starts off amazingly and then turns spectacularly underwhelming - 4 dice at 3 is great, 2 more over the next 17 levels while taking new maneuvers from an ever shrinking list does not a late game powerhouse make.

Which leaves the eldritch knight, which starts off underwhelming at a point where the base fighter is already good and won't notice that but in contrast to the other two constantly grows in both depth and breadth of ability, gaining abilities like invisibility, fireball, shield and banishment.

[Sigreid]

I like it multi-classed with 2 levels of evoker wizard. Dropping a fireball at your feet to thin out the mobs is fun.

[greenstone]

Because using mage hand to spread caltrops 30 feet in front of you is fun. Because casting shield and taunting the bad guys is fun (nya nya nya my AC is now 26!). Because a hulking plate-armoured figure teleporting next to the enemy mage and counterspelling them is hilarious.

I like my EK for the versatility. Mage hand is endlessly useful, as is minor illusion. My EK is usually standing right next to the heavily-armoured opponents, so shocking grasp will be a a great choice when I get war magic.

At later levels, being able to haste or fly myself, without using up the concentration of the party mage, is going to be extremely useful.

[Retief]

A battlemaster fighter with great weapon master will outdamage a eldritch knight, sure. However, booming blade/green flame blade + war magic will match up decently against most sword and board builds. A two level wizard (bladesinger) dip on a a dex based sword and board build will provide a lot of ac combined with competitive damage and more versatility than most fighters can boast.

If you really want more damage, you can consider doing something like eldritch knight 7/bladesinger 2/arcane trickster 11. You give up some defense and 3rd-4th level spells, but 6d6 sneak attack damage helps a lot on a build with relatively few attacks per round, and you get some of the most ridiculous opportunity attacks in the game. Pick some spells with decent slot scaling, and you will still get value out of your higher level spell slots.

Also, eldritch knight 7 is sort of silly with the scag cantrips. Assume 18 str or dex and 16 int. A two hander without great weapon master deals 2d6+4 damage per attack. Throw in great weapon fighting, and you get 12.3 average damage per hit and 24.6 damage per round. A sword and board ek build would deal 1d8+4 damage per attack, for 8.5 damage. With war magic, you get two attacks. Green flame blade at level 7 does an additional 2d8+3 damage for an average of 12 additional damage. That ends up being a total of 29 damage per round, and this is assuming a shield + the defense fighting style. If you don't care about the ac and are ok with a strength based build, a greatsword and great weapon fighting would add another 9.2 damage per round.

[Foxhound438]

you have all the base fighter stuff with the added benefits of a decent ranged option from cantrips if you're a str fighter, and efficient tricks for when they seem good at the time. The spells you get are pretty far behind a full caster's but you don't really need to be casting high to get good effects. Fireball holds decent effect even at the late level you get it, since it can seriously soften crowds of mooks.

[Kane0]

Because on the gish spectrum the EK leans the most on the warrior side. For those looking for a warrior with a dash of magic as opposed to the battlemage counterpart an EK is a fine choice. They can self buff and provide a little of their own utility as well as some blasts if necessary too, all while maintaining the most amount of extra attacks and ASIs available. Add in war magic for excellent multiclass and damage cantrip options plus a flavorful bonded weapon and you have a well rounded, fully capable gish in a can.