they are both great soloing schools, ice is great since I have an exalted ice and he has 90 damage and 50 resist universal, but with myth's op aoe spell for exalted, it is amazing and myth has great damage wise, decent resist and decent ration block and critical! remember if you pick ice they aren't so defensive as you think they are, my ice can reach 700 critical, its like a better version of storm but with more health and people underestimate them
should I make a myth or ice wizard? which one is more fun to play with and which one is better in pvp?
The answer depends on the style of play you like. Create one of each and see which you like. you can have 6 wizards on one account.. and can delete any you do not like. Personally I prefer Ice over Myth but that's just me.
I do not PvP... but Ice paired with Life as secondary is a difficult wizard to beat.