My first pair were Penny's and I loved them. Juliet's are also great as others have mentioned as they fit a wide range of faces and are easily available. I've got X-Squared's as well and those are my go-to sunglasses. I still wear the Penny's and Juliet's on occasion. You will enjoy whatever you go with. X-Metals are awesome.
I love my XX on my big head but also look good in Juliets. If you have a small narrow head you can even pull off some Pennys but they are not as easy to find cheap..