For the purposes of solo delving as Preservation we will be equipping Brann as a Tank, besides that we need to select a combat curio and a utility curio to enhance him further, these are the options:

Combat Curios

For healers i am recommending 1214902. It is very easy to use and results in a very consistent power increase, the drawback of occasionally having to dispell Brann is really minor and you can usually take care of it without any trouble at all. Other option can be 1215366 for a more bursty time of damage coming from Brann when you get an egg summon

Utility Curios

For Utility my recommendation is 1214703. Just a very simple stat gain that works everywhere and gets stronger the more you explore the delves. 1216676 and 1215254 can also be decently good options.