Tabitha is definitely my favourite of these - really lovely, as long as you don't mind at least 50% of people claiming it can only ever be a cat's name. Think it's probably the definitive Marmite name. 
Ottilie is nice too, but I'm not a fan of Tilly, which is the obvious shortening. Lara is OK - inoffensive, but I can't get excited about it. And Olivia, pretty as it is, is way too popular for me.