I suggest you to try services provided by eurodns.com. They are reputable European registrar with nice prices and knowledgeable support
There's not much technical expertise needed in order to register a domain so I believe recognizing a registrar to be the best for me boils down to how accurate there data is when doing a check if the domain you wish to buy is available or not, how fast they can register a domain, how easy you can change the dns settings for your domain, the cost involved (domain transfer fee, redemption fee in case your domain will expire, private registration fee, etc) and their technical support. Overall for those common tlds and some others, I will have GoDaddy and 1and1 as my option.