Depends on your budget... I think only the 800/5.6L IS is more expensive among the Canon lensesFor example, the 600/4L IS IIIf I were just starting out, and being on a budget, would this be a good lens?
The portrait EF lens budget ladder looks something like (going to more expensive lenses)
85/1.8 or 100/2.0
85/1.2L II or 70-200/2.8L IS II
To me, the 70-200/2.8L IS II is the perfect middle ground with its zoom flexibility. Sure, you don't get the ultra-thin focal depth, but sometimes it's actually preferable to have both eyes in focus The Sigma EX 85/1.4 might be a great alternative as well, sitting between EF 85/1.8 and EF 135/2.0L. A disadvantage of the zoom (apart from price) is that it is heavier than the primes and brings attention with its size and white colour.