Magic Initiate is REALLY good! Martial Adept is GARBAGE. How is a single superiority dice, ONCE PER SHORT REST, that doesn't scale in level even ANYWHERE close to a two cantrips and a good defensive option once per day?! Booming Blade in particular is a super popular cantrip to buff rogues because it stacks favorably with Sneak Attack.
I never said it was a great feat. What I said is my players who have this
"garbage" feat Martial Adept, are not overshadowed at the table. So even with this WEAK feat and only a 16 dexterity at 10th and 12th level I am still not overshadowed and honestly, the feat is part of why, even though it makes for a weaker character.
Also for what it does do on the Scout - I primarily have it for the quick toss maneuver, which lets me cast a spell or do another action and still land sneak attack - once a short rest. I like it, it is FUN. It lets me get off an action other than attacking in the first turn of combat and then still get a sneak attack that turn. I can do this in roughly half of my fights. So it is kind of like action surge in play. I can only use it once per short rest, but when I do I more or less get almost 2 turns worth of stuff.
I can tell you how I used it in the last battle - I started the battle hidden in a copse of trees while party members negotiated (and failed). I have a pretty awesome dagger that does an extra 1d6 psychic damage, I use it with BB a lot. Well when the battle started, I won initiative and used quick toss to fling the dagger at an awakened tree of some sort (with advantage and sneak attack). I hit the tree-thing and one-shotted it. Then I pulled my heavy crossbow off of my back and used my action to ready an action to shoot the great oak (Boss) once the paladin got within 5 feet. Paladin closed and my reaction landed another sneak attack against the great oak. I can do that sort of thing in the first turn of roughly half my fights. 2 sneak attacks in one round the first turn of roughly half your fights .... with a 1d6 damage bonus to boot ..... that is not optimal, but it is also not terrible.
Is it as powerful as a +2 dex or elven accuracy (character is a half-elf)? Probably not, but it is still cool and fun.
I also have grappling attack on that character, but I do not use that nearly as much.
As far as my second character, that character has 2 dice and 3 maneuvers because she also has superior technique fighting style. With her I have several ways I use it:
1. Disarm Attack, then use mage hand legerdemain to pick up downed weapon (assumes mage hand is already cast and near). This is a bit situational, but it isa game changer if it lands and can greatly change the outcome of a battle.
2. Menacing Attack to control movement: Use menacing attack, if it lands enemy can not close with you. Depending on the situation it may cause a completely lost action and with a failed save it always causes disadvantage to enemy attacks. So use one of my two dice to steal an action from an enemy and/or control the battlefield/movement.
3. Pushing Attack: When I use this it is usually one of two ways: use it on someone already under grasping arrow, which causes 2d6 slashing in addition to the attack damage and 1d6 superiority dice. The other thing I do is use it with booming blade to move the enemy away from me. This does not cause BB damage this turn, but it puts the enemy away from me and under the BB effect so he can't close on his turn without taking damage. The character is primarily an archer, so it is good to have a way to push someone out of melee range.
So, she can do 2 of the 3 things above with every short rest, in addition to her two arcane shots per short rest and her action surge. Again as powerful as Archery and a +2 Dex or Sharpshooter? No it isn't, but it is more fun.
A good, clever, player using Minor Illusion is WAY more impactful than 'This turn I add 1D6 to one of my attack and the guy is MAYBE knocked prone'.
Well I have minor illusion as well .... and ANY martial could get it in the same fashion I got it.
Minor illusion is awesome, but casting it in combat means no sneak attack that turn because it uses an action. That is a high opportunity cost. However, since I have martial adept with quick toss, I can cast minor illusion and still get sneak attack in that same turn. As a matter of fact I can use the combination of these two feats to
enable sneak attack when I would not otherwise have it - move within 20 feet, cast minor illusion putting up an illusion of a 5 foot tall wall between me and the enemy (making me unseen), then quick-toss my dagger through that illusory wall with advantage and therefore sneak attack.
Magic Initiate is an order of magnitude better than Martial Adept. For the price of a feat, Martial Adept should give you some martial weapons prof AND a fighting style AND 2 superiority dice that improve with level.
I am pretty happy with it as is on both characters who have it (although they use it in different ways). If I wasn't I wouldn't have gotten it for either of them and I certainly would not have got it a second time. I gave up an ASI or a feat like sharpshooter to pick it up.
The most important thing is I am having fun, which based on other posts, many of the people taking ASIs and other stronger feats on their martials apparently aren't.