I don't really get the Polearm Master love. Any fight that matters, I've got spiritual weapon up, and that means I have a reliable bonus action attack whenever I need it. The control is nice with tempest, but I can't justify spending a feat on it. Anyway, I've only had experience playing War and Tempest. Here are my brief thoughts...
War: Good multiclass. Your fighting ability doesn't scale well enough, so eventually you either multiclass because you want to fight or stay cleric and become a caster. I think it's a terrific multiclass with fighter and gives you a smooth play experience and power progression from 1-20.
Tempest: I'm in a seafaring campaign, so this is kinda cheating...but it's awesome! Just enough of a boost from the domain to be pretty effective as an AoE blaster, along with all the other stuff the cleric does well. The only thing that bugs me (perhaps irrationally) is the way my at-wills tug me in different directions depending on my level: 1-4 weapon attack is better; 5-7 sacred flame is better; 8-10 weapon attack is better again; 11-13 back to sacred flame. It's really only an identity crisis when I don't have something better to do (i.e. cast a real spell), but it vexes me. Even when I'm not blasting, it's fun standing in the front line with spiritual weapon and spirit guardians up, with Wrath of the Storm at the ready, making myself a supreme annoyance for the enemy.