Me and a friend have been teaching a couple of new players how to play the game and it has been an experience. It's furthered my understanding of the rules and really helped me further tune into my decks because it slows the game down a bit, and I let the new people play my competitive decks. It's been fun!
My favorite deck that I've spent the most time with/on is ezuri. We all know ezuri is a lower tier commander, but I've done what I can to make it as aggro as possible with the exception of a few expensive cards I can't afford...looking at you [[Eladamri, Lord of Leaves]]. When I pass my decks off, I love giving them a breakdown of how to play it, both for their benefit, but also for mine.
Ezuri. Aggro. Best in 1 on 1 situations, but I've won in 4 player commander. In 1v1, if you aren't swinging by turn 2, you possibly drew a bad hand. The idea is to ramp as fast as possible. The deck is streamlined enough that you should be able to tutor a Priest of Titania or Elvish archdruid by turn 2 or 3. Ideally, by turn 3, you'll have priest and 3 other dorks out. Turn 4, you should have Umbral Mantle or sword of the paruns on the board and can equip it. Go for infinite mana, cast ezuri and overrun your opponent(s) to death. There's no removal, just aggro.
Kess, draw your library and/or tutor for Thassa and demonic consultation. This is a slow deck with counterspells until I can add more meaningful ramp. As you play, always leave mana behind for counterspells. When you have enough mana to counter a potential threat and pull off the win con, do it.
Lathril, Blade of Elves. Similar to ezuri, completely aggro. Overrun the board state with tokens and go wide. By turn 4 or 5, you should either make infinite tokens, make infinite mana, or combo out and tap lathril for her ability. I haven't pulled it off yet, but umbral+priest of Titania/presence of gond attached, and lathril should he an infinite win. Make a ton of mana. Off Titania, then untap and make A ton of tokens, then move umbral Mantle to lathril during combat. Tap priest for a ton of mana, use that mana to untap and tap lathril 4 times dealing 10 damage to each opponent with every tap.
My aminatou deck is unaltered out of the box. The idea of course is to play top deck. Rearrange the top of the deck in the best way to benefit your next play. It's slow and cumbersome, confusing at first, but once you can pilot it, it's lots of fun to play. The key with this deck is to he unassuming until you know you have the board. Use board wipes only when necessary!
Edgar Markov is very casual because I haven't spent enough time. Basically though, make vamp tokens until you can draw into/tutor for exquisite blood and sanguine bond. It can be fun to play in the right setting, but it still needs a lot of help.