So my real question is my eventual multiclass choice, and the two other CH based casters i keep considering are sorcerer (wild mage) and warlock (and possibly hexblade, but im seeing a conflict of loyalties there - he doesn't need any more, really).
Unlike in some earlier editions, multiclassing is not only not the only path to a powerful build, but it's somethign where you need to work to make sure you don't accidentally shoot yourself in the foot.
You can definitely make good multiclassed characters, and Paladin / Sorcerer is a classic, with Paladin / Warlock also workable. But a straight Paladin is also in the front part of the power curve and will also serve you fine.
There are a lot of people asking "why do you want to multiclass" and that's the question of the hour. What do you specifically want to get out of it? Ranged options? More spell slots for Divine Smite? Higher level slots for spellcasting? Utility?
Here's some contradictory pieces of advice:
1. Stay straight paladin. There's a cost of opportunity to multiclassing and paladins really do get a lot of stuff. They also get some great spells which you can't pick as spells known except with paladin casting levels.
2. Grab a single early level of sorcerer or warlock (hexblade). Taking sorcerer as your first level could get you CON saves which are good for keeping Concentration on spells, but won't give you heavy armor and with a STR-based Half-Orc it's probably the route you want to take. the CHR-to-attack part of Hexblade isn't all that useful either, but was so the Shield would be on your list - a very useful spell for melee. (It's already on your sorc list). Also both get the melee cantrips from Sword Coast Adventurer's Guide that will increase your melee damage and give cool effects, though aren't compatible with extra attack which you get at Paladin 5.
3. Stay paladin until well established - it's a long road - and then multiclass. Well established - well, 5th is extra attack, 6th is the minimum for your signature aura. Not before then. 7th is your subclass aura which could be quite nice. If you're already 7th you don't want to miss you ASI at 8th, that's one of the ways to accidentally shoot yourself in the foot. Then you have the choice of saying in to get your level 11 power bump or not (and the ASI at 12th, 11 -> 12 gives you a full caster level when multiclassing).
3a. Sorcerer will give you higher level slots, for actual casting. Twin spell, good CON, and you can buff yourself and an ally quite nicely to accentuate your paladin abilities. Remember that you can only pick spells known that JUST your sorcerer levels would grant, so you'll have slots well above what you know spells for. You can upcast but you'll not have higher level spells for a long time. Sorcerer is the long haul - it gives you enough to start that you don't really regret not taking more paladin levels too much, but gets better once you have 5, 7 or more levels of it. If your campaign won't realistically go past the pre-teens, this doesn't give as much. If it will definitely go to 20, this might be the way to go.
3b. Warlock gives a whole different casting mechanism. It doesn't add to your paladin slots, it adds a separate track fo them that comes back with a short rest. 3 levels of warlock give you invocations, patron, pact, and two 2nd level spells slots per short rest for divine smite (+3d8 radiant damage) or casting. This will give you a quicker pay-off then sorcerer but doesn't have as much top-side potential for synergizing with paladin - so if you are going to end pre-teen or early teens that will give more, if you're going to 20 sorcerer will surpass. But rememebr, you still have to play it all the way up, so maybe that's okay - get your power to play with for more of the campaign even if it's not quite as powerful at the end.
Hexblade has it's curse which is nice, especially with the Half-Orc racial and both synergize nicely with Oath of Vengance (and the Great Weapon Fighting feat). But that's very "one foe" focused. Other oaths have a lot of good things in them, whcih may lead you to other patrons. The Fiend gives temp HP on every kill which can just keep you going. Celestial (from Xanathar's Guide to Everything) gives you bonus action healing. At 3rd, while Pact of the Blade seems intuitive, Pact of the Chain can give you a familiar that can use the Help action to grant advantage during combat.
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