man are you asking for a debate here.
probably going to come down to personal opinions and experiences and such. If you’ve done well with Italy you’ll like it, if you’ve long wanted Italy to be playable, you’ll like it, though you might think it’s underpowered.
If you have played as Italy and had the allies focus on you first, you’ll dislike it (the russia of the axis, eh). If you’ve played as Italy and been ignored and swept up into Moscow or UK, you’ll like it. If you think you should be able to buy 3 bombers each turn from the start, you’ll dislike it.
Just prepare for possible wild contrasting views on this, it’s like asking a group of strangers if you will like one game better than another, in the end it will come down to you and your attitude towards it. If you draw Italy when you play, look to maximize it for your side and go after it. You may not be prominent in every battle, but you can make a big difference.
as for me, I like Italy, I have seriously kicked some butt with it and have changed my friends attentions with it in games. I’ve added Italy into revised, played the AAHRE with it and even into Europe, so it’s a nice addition to me.
As for China, they actually aren’t a separate power, they are controlled by the US and if someone wants you to play them as a separate power, you’ll need Funcionetta’s mod.