Totally depends on requirements when you join (and in some cases just after you join!) I had 3500 hours and got A320... A colleague joined with 1700 and got 777.
They are 'trying' to put all new starters on the 320 to standardise fleet progession, BUT it's not 100% obviously.
Anyway, as tiring as the 320 roster is for a few days every month, it has a great network, layovers and earlier upgrade possibilities.
Get here and get what you're given, try to enjoy it and you will find it a very rewarding place to be.