I heard from both Italian people and also here on Forum that if you do everytime the same mission, your loot will standardize and you won't earn the best loot.
Sorry, but who told these nonsense to you? o.k. - to the missions:
Every mission-place has three different opponents! There are 5 loot-classes of mission-opponents:
1. very poor
2. poor
3. medium
4. good
5. very good
So, you have to find a place with many good and very good opponents. Dragons Nest in Talfour is the best place for Silver because you find there
Dragon (Black and white mission) - very good
Pheonix (Black mission) - very good
Lindwurm (so its called in German - white mission) - very good
whitcher (black and white mission) - good
So, you have there 2 very good and 1 good opponents
very poor opponents give 5-11 x your own level silver per 20 points mission
poor opponents give 8-13 x your own level
medium opponents 11-18 x your own level
good opponents 15-23x your own level
very good opponents 22 - 35 x your own level
All this at "normal" loot. "Great loot" about 90% more and "phenomenal loot" about 150-200% more
All other places are not really good for missions - besides.....
Ramstill - Arkane hills............................why????
There you have
Unicorn (good opponent)
Pheonix (good opponent - black mission)
Lindwurm (very good opponent - light mission)
lucky knight (poor opponent - black mission)
kultist (poor opponent - light mission)
The class of opponents are lower than Talfour, so the loot is lower too , but.....
1. Every opponent gives karma!
2. If you have the dog, you will find items from time to time. Your dog is a little thief.... - he takes the items from the trader of this town, where you make the mission. And in Ramstill and Brant you have best and thatswhy most expensive items in Armor, Shield, Jeans and Hats - so you have a very good chance to find some very expensive item!
You have 1% chance to find something - so in 100 missions you find 1 item. At low levels this is not so important - but I am level 139. When i find an item in Talfour, this is sold for 30.000 - 150.000. Items I find in Ramstill will be sold for 200.000 - 400.000. When you are level 180 the difference is more higher - in Talfour 300.000 - 600.000 per item, in Ramstill 800.000 - 2.500.000 per item....
So special for knights with small levels:
good mission-places are all lighthouses (Sedwich, Waile) and Talmet (Forest) and Hatwig (Forest) - than Brant (Fire mountain) - than Ramstill (Arkane Hills)
At last some words about pheonix - he is at very good class ONLY in Talfour! At all other mission places pheonix is only a good-class-opponent. I told this to the support as a bug 5 or 6 years ago... - but they said, this would be no bug, this would be a game feature...
o.k. - hope to bring some light into the darkness of missions 
Omen