I haven't seen Roxy, so can't comment on her, but she sounds a goodun'.
Sexy Amy is a good punt. Very pretty, thin, and decent service, though I think she crams in as many as possible, so I have felt a bit conveyor belt with her. She wasn't averse to answering the phone between pops with me (I have an hour), to take another booking, which I wasn't happy with. However, all in all very good.
Nikki is a fuller figure (not fat, but no waif). Also pretty, with hair extensions, and bigger tits. Her service is excellent, though she doesn't suffer fools gladly.
Both girls English is fine, so no probs there, and both offer fantastic vfm against most other Cardiff girls IMO.
Hth