Upgrade to FF

I have the T2i since 2010 with a lot of canon EF lens (three L)
Only have the EFS 18-135mm as a kit lens
I like to upgrade for a FF but don't know what to choose
I'am a bit of bigginer liking children portrait an landscape no sport nor birds

I've problems using lock AF and recompose with portraiture (cant' get good result even at f/5.6)
Is the 5d II is a good choice or shuold I consider the 5d III (best Af)?
I know the last is very expensive here in France (3145 euros).
--
az03