My semi-educated view of tank history: Monks are generally the most stable tanks to heal (smooth damage intake), but paladins fare better without a healer than monks do (better selfhealing). Don’t know if all this holds true for DF though.
Both of those are good tanks. Prot palas have great utility (blessings, auras, offhealing), while monks have more mobility and bring the physical damage debuff.
Generally speaking monk is quite more “sturdy” as a tank, as his mastery makes him take damage way too steadily. On the other hand, pala is abit less “tanky” and you have to put abit more effort into not dying.
Here you are quite out of luck. While both spec might have a “ranged option”, there is a good chance that the optimal way to play is for them to be in melee (and especially paladin).
Both of those specs have little chance of being “meta”, although monk is generally good in m+. I would focus more on what you enjoy to play as.
All of this is based on feel/utility/talent trees. Actual number tuning will play a role, but we currently have no idea what blizzard is gonna do there.
If you want to stay away from HP hopping? I would pick paladin on this as a tank
While there is no doubt both tanks are perfectly capable of doing a +15 in time, Paladin would fit in on the “sturdy and no hp hopping” Well, will be some hp hopping on paladin, but they compensate it with self healing just fine or using their defensive CDs. Brewmasters is more of a constant drip of health with occassional 10% - 20% HP off from nowhere with no context, which means fast reactions is needed
Brewmasters can be real tank monsters in the right hands, but takes a while to get the hang of it when it comes to balance incoming damage and stagger, also knowing the tricks you got up your sleeves to give the healer a chance to catch up
Additionally with paladin, you got plenty of group utility to provide: like Hand of Freedom, Blessing of Protection/Spellwarding, frequent interrupting with avengers shield and rebuke combined, toss a free cast word of glory on a member that is in a pinch
Holy paladin doesn’t feel fun at the moment, whereas mistweaver supposedly feels really good to play now. So if you’re going to heal a lot, I’d say go with monk.
Prot pala.
Now we have a Brez to bring to the table and with the new talents we are very solid. We are also way more flexible than monk for general and solo content.
Expect the usual suffering in s1 as we are monumentaly dependent on having at least 20% haste to work properly, and the usual “we are slow af”.