Srna or rafinha

Morning guys ;)

I need some help from you FM veterans ;) Im looking for a RB for my liverpool team ;)
I just cant seem to find anything decent, he schould be about the same skill as Glen Johnson (or maybe better?:p) and not older than 28 years.

My budget is around 20 mill £ so you got any tips? Or someone close to wath I wrote?

Thanks in advance :)

Darijo srna great attacking player will score goals great free kick or rafinha young shalke brazillian guy who is just as good
Van der wiel if you can get him... nothing amazing but steady right back....
renan is extremely good already right from season 1 and as he is young he has potential to be even better!
Darijo Srna
Kyle Walker
Micah Richards
Bakary Sagna
Dmytro Chygrynyski
albert botia has the most perfect stats for a full back and he can play cb too
srna on a free 2nd season is a beauty, i got 3 seasons out of him so far and he's still one of my most consistent performers.

also joao perreira has a minimum release clause of £3m and looks pretty good for that price