Tips

Echo Knight: 30ft Fun	As Echo Knight, your Echo is only destroyed through its innate condition of being 30ft away from you at the end of your turn. You can utilize this in a few ways. *You can use a readied action to move 30ft outside of your turn, meaning at the start of your next turn you will be 60ft away from your Echo while still having your full action economy. *If you start your turn exactly 30ft from your echo, you can move your echo 30ft further away from you, 'then' move it another 30ft using its innate movement, then on the same turn use your bonus action to move 60ft away from yourself at only the cost of 15ft of movement and your bonus action.
Echo Knight: Objectification	As Echo Knight, your Echo is an object. This makes it immune to most effects, abilities and mechanics in the game. These can include spell effects, area of effect spells and legendary actions. Even though it only has one hit point, it has a surprising amount of combat utility because of this - especially when used in tandem with the Sentinel feat to punish your opponent for leaving it up.
Conjuration Wizard: Pets for Days?	As Conjuration Wizard, you eventually gain a class feature that allows you to never have to roll concentration checks for your conjuration spells. Before Tasha's Cauldron of Everything there wasn't many good targets for this, but after Tasha's came out they added quite a few fun pet spells for Wizard! A Conjuration Wizard that summons pets in combat actually seems like a pretty fun build.
Monk: Why bother?	Why does WOTC even bother with this class? Why do they hate the idea that monk should be able to deal competitive damage with the rest of the party? Why is Fighter legitimately better for unarmed builds thanks to the 1d8 fighting style they get? The only time you should consider playing playing monk is when your DM is allowing the old, pre-nerf UA builds. Pre-nerf Dragonic Ascendant with the Gem Dragonborn race is pretty fun and Astral Self pre-nerf is pretty wacky. I don't want to play as Hexblade or Fighter when I want to play as a martial artist...
Primeval Druid: Surprisingly Fleixble?	This UA just came out - pretty sure people are sleeping on this one pretty hard. Its less DPR-bursty then Moon Druid at early levels, but scales very well into the late game. Rewards creative players who can take advantage of having essentially a second action each turn, since, technically, nothing is keeping you from choosing a primeval companion with two arms and two legs to wear armor and weapons ( Unless your DM is mean, but even then it can wear barding and carry tons of equipment. )
Monk-Moon Druid - the ultimate unicorn build?	Transforming into a tiny spider with martial arts die and full access to your class feature list is pretty funny, but monk is written in a way where they are comically bad at multiclassing - meaning that a 2 dip is practically suicide if you are starting the game at a level before 7.
Water Breathing - Way Too Overcosted	In the five games I have been in in the last four years, I have only actually swam twice in game. Grungs are powerful on paper, but I would hate to be that Grung monk player who asks their DM where the nearest watering pool is every. single. session.