I certainly don't think this question has been posed before on this thread, but as a big Dwarf player myself I'd be happy to offer advice!
To start with, GW still sell Ironbreakers, Hammerers, Irondrakes, Longbeards, Gyrocopters and Gyrobombers, along with Fyreslayer Vulkites who can be used as Slayers (I painted a unit of them as my first entry in my Painting Blog and they fit on 20mm square bases OK providing you fit the models together in a unit as you glue them to their bases) so you're OK for elite infantry. The SC Greywater Fastness box is a decent starter which gives you King Belegar (who can be made into an ordinary Lord if you wish), Grimm Burloksson (who can be made into a Master Engineer), 10 Ironbreakers/Irondrakes and a Gyrobomber/Gyrocopter, so that will certainly fill out your character and elite slots for a small starter force. Unfortunately the same cannot be said for your Core choices (unless you field wall-to-wall Longbeards as your Core loadout which isn't a bad move but sacrifices potential shooting capabilities), as GW for some dumb reason scrapped the Dwarf Warrior and Thunderer/Quarreller kits, as well as the Cannon/Organ Gun kit, as part of their terrible Empire-and-Dark-Elf-Alliance Cities of Skubmar idea, meaning you're going to have to search elsewhere for those.
With regards to other manufacturers, Mantic's models have a very different aesthetic to the GW models, so you'd have to choose which aesthetic to go for, and personally I'm not keen on the broad, almost square, heads of the Mantic ones, but on the other hand they are affordable models with troop types to cover most of the army list.:
https://www.manticgames.com/games/kings-of-war/dwarfs/
Middle Earth Dwarves are a bit short and thin as you've said, and also don't have many of the options usable in Warhammer Fantasy, though Oathmark, despite having a similar aesthetic that would look significantly different to Warhammer Fantasy, is probably the only good potential source of Miners (which were kicked when AoS first emerged despite being a great plastic kit) out there with their new Dwarf Light Infantry box:
Avatars of War make plastic sets of Dwarf Warriors, Dwarf Rangers (who can also be used as Quarellers if suitably converted or mixed with the Warriors kit) and some alternative Hammerer and Slayer unit sets:
https://avatars-of-war.com/sh/en/97-plastic-regiments
Dragon's Lake Miniatures make some interesting sets that seem to be reasonably affordable, including a Cannon that can be made into one of two different configurations, as well as Warriors, Slayers, Gyrocopters, an Anvil of Doom, a Grudge Thrower and various character models, including Lords on an Oath Stone and Shieldbearers, and even a Throne of Power that could be used to proxy Thorgrim should you wish to take him.
https://dragonslakeminiaturas.com/categoria-producto/miniaturas/enanos/
They seem quite affordable, but the website's in Spanish, so unless you can understand Español, you might not be able to understand how to buy your Dwarfs in the first place.
And Fireforge Games are set to be releasing their own Dwarf range soon, that has aesthetics more in common with the Empire than proper Dwarfs, but has a set capable of making Quarrellers or Thunderers, as well as Hammerers. The models are currently in Kickstarter at the moment but will be starting shipping in February, meaning they will probably appear for sale on Fireforge's website at around March time:
https://www.kickstarter.com/project...-multi-part-dwarves-in-28mm-scale/description
Hope those are helpful. Unfortunately it isn't the best time to start Dwarfs because GW were so stupid about getting rid of so many of their models for their feeble Cities of Sigmar army list (which really should have been divided into more factions with each of them getting some more models), but Dwarfs aren't too difficult to find on EBay or in shops that stock second-hand stuff and not as pricey as some of the other armies that are OOP, and maybe there will be a revival for either AoS or TOW when it arrives.
