What's better, Phoenix or Phantom?

[Piedmont]

I'm going to restart now that I know what I'm doing, I'm a mage.

To others, I read somewhere that the Paladin in Marsh Swamps can randomly sell Resurrection but I did the thing of start a new game, save, talk to the guy to get out immediately, head right to the Paladin in the Marsh to see if he had it. If so, reload your save and do the trials etc. knowing resurrection will be waiting for you in the Marsh. After 4 hours of doing this (~200 attempts) the highest casting cost spell I ever found at the Paladin was 2000 gold... a far stretch from the cost of resurrection so that tip seems bogus.

One thing I noticed was going to the other land straight out the castle there's a tower that sells higher level spells for a beginner, sometimes it sold Phoenix or Phantom Army. Those were my favorites in HOMM. I'm thinking of doing my plan above except going for that tower for one or the other of that spells. I'm wondering which do you think is better? Thanks