I guess I understand the appeal of Tree of Life somewhat but I think perhaps one needs to be more spiritual to truly appreciate it. I've said before that the main section of the film dealing with the autobiographical narrative of growing up in the conservative southern suburbs was what moved me. The first and last portions dealing with Penn and all the cosmic stuff felt like fluff to me, like Malick was departing from the deeply human characteristics of his core coming of age narrative to pontificate beyond the scope of that narrative, finding links that probably only a spiritual person would see. His defining films have all explored humanity's connection with nature and the processes which uproot that closeness (war in Thin Red Line, tribalism in A Hidden Life, colonialism in New World, etc), but Tree of Life goes much farther than he typically does and unless you can stick with him for the whole trip (I wasn't), it's going to feel like the film comes up short in comparison to his others because it has so much more to prove.
but any list including Phantom Thread and Inside Llewyn Davis is ok with me.
Eh, I'm a pretty staunch atheist and would definitely not call myself spiritual, and The Tree of Life is still without a doubt my favorite film of the decade. It gets better and better with each rewatch. I don't share Malick's faith but I admire the way he expresses it in his films.