Depends on how big she wants it.
If she wants Iphone 4 size,get her either an overpriced Iphone or get here a samsung galaxy S2 for nearly half the price.

Pretty much the same,only slightly different in performance and most differences are in samsung's advantage but they're all quite expensive,usualy 150+ but over here in Ireland my dad managed to get one for 110 I believe.(don't ask,deal involving changing to vodafone for 50 euro off...Other side of the street was a meteor shop which selled sim-cards for 10)...
If she wants an average sized one I think the samsung galaxy young,galaxy mini and most HTCs might be the best ones,they're around 100 I believe...
IMHO apple is way too overpriced,barely any hardware difference between most androids.
EDIT:seeing you are considering a 300 euro phone I would recommend a samsung S2(perfect size) or S3(slightly too big IMO but more hardware).
But of course this all varies on your taste.