Hehe, this is a sensitive subject. It's like which is the best computer Mac or PC. There are also some mysteria around the "Volvo" fluids. Anyway here is my two pennies. Let me hear what you think.

Engine oil - Any fully synthetic. 5w-40 is a good range in my climate - 20'c to minus 20'c. Change oil and filter each year.

Coolant - Any coolant that is approved for aluminium is ok. Cheaper coolant you have to change more often (about 2yrs) since it degrades quicker. Deionized water (batterywater) or premixed coolant is a good idea. Change every 4 yrs.

Auto transmission - Any Dexron III approved oil. Flush every 4-5 yrs.

Break fluid - Volvo Dot4+. This one I wont skimp on. Dot4+ is different from ordinary Dot4. The plus means a higher boiling point. The Dot spec is also a bit loose on the aging factor. There can be a world of difference between two Dot4 brake fluids. Change every 3-4 yrs. Change every 1-2 years if you use cheap brake fluid. But I dont recommend it. Dot 5 is also not a good idea (you have to change the break system).

The special Volvo brake fluid is actually made by Basf, and its called Hydraulan 407-1.