On the subject of FFIV, I have to say it was my favorite in the series. I loved the battle system, I loved the character development, I loved the story, I loved everything about it. The music was the best of any FF, IMO.
One fault I did find with it was that it was a pain to level up as much as they wanted you to between each dungeon. That's one of the reasons I loved CT and CC so much. If you play through either game the first time, and fight every enemy once, you're a sufficient level to beat it.
The fight with Zeromus is actually VERY easy. Kain jumps, Edge throws stuff until he runs out, don't heal him, physicals until he dies. Rosa attacks with holy, Rydia with Nuke, then Rosa heals party with Cure4. Cecil is physicals the whole time. Then when Rosa dies, make sure to have a few Elixirs. Like 5 or 6. Physically attack with Cecil 2 turns, then use an elixir. He's gone in no time.
I solo'd Zeromus with a level 61 Cecil once. I made sure that all of my characters were dead by the time I [SPOILER] reached the bottom of the Crystal Tower [/SPOILER] and ended up using 13 or 14 elixirs.