Armorers/blacksmiths at forts around Toussaint that you have to libirate from bandits. Not only these merchants have like 12000 gold on them but also give you preferred rates at their shops 
Other than that the grandmaster craftsmen in Toussaint. He has just about as much gold, just no discount, he's also available right from the start.
If talking about the main game only, the armorer at the Hierarch Square usually has a good amount of gold on him, around 8000. Also the two craftsmen at Kaer Trolde usually have a good sum on them as the pair at Kaer Muire does. If selling junk items, then Passiflora and Kingfisher have no alternatives.
Other than that the grandmaster craftsmen in Toussaint. He has just about as much gold, just no discount, he's also available right from the start.If talking about the main game only, the armorer at the Hierarch Square usually has a good amount of gold on him, around 8000. Also the two craftsmen at Kaer Trolde usually have a good sum on them as the pair at Kaer Muire does. If selling junk items, then Passiflora and Kingfisher have no alternatives.
If you have a lot of excessive expensive swords and armor you may keep them in the stash and sell later when you will craft Master Items - high-level crafting costs a lot of money, so you can get your money back immediately. As for the best merchants - yes, Novigrad armorer and later master blacksmith have a lot of cash and best prices (before Toussaint became accessible).
Also there is good halfling alchemist near Katarina's brothel - he has prices times better then average trader, so if you need ingredients than it is wise to buy from him and return you money by selling monster parts. Same comes for junk - it is good to buy alcohol for White Gull in taverns (can't be looted) and return your money by selling animal hides etc - it's more profitable then selling them to regular merchants.
Also there is good halfling alchemist near Katarina's brothel - he has prices times better then average trader, so if you need ingredients than it is wise to buy from him and return you money by selling monster parts. Same comes for junk - it is good to buy alcohol for White Gull in taverns (can't be looted) and return your money by selling animal hides etc - it's more profitable then selling them to regular merchants.
CharmCitysKing;n7966510 said:
I normally rotate between the weaponsmith, armorer, Hattori, bookshop, marketplace herbalist, and halfling hebalist with the actual shop. Together with almost the same selection of shops in Oxenfurt, I never lack for a place to offload loot.
Although, most recently, I've simply been leaving loot on the ground unless I need it. I've found I truly don't need much money once I know what I'm after. Just grabbing gems, nice weapons, or extra-tasty monster bits is more than enough with the normal pay for witcher contracts.