I like Dynadot best at the moment because of their user interface that is easy to use. Not the best looking but it is logical.
I used to use namecheap a lot but their prices are not competitive anymore, even with the discount codes or the golddeal discount I have with them.
Internet.bs is the cheapest at the moment (cheaper than Godaddy with $7.49 coms including icann fee). I have a few domains with them. They are not bad. It takes a while getting used to.
The features I expect in any domain registrar are:
1. multiple pre-define a whois profiles which I can save and then I can assign that profile to multiple domains in one go.
2. Being able to see what domains use what whois profile.
3. Saving common nameservers and then chosing them from a list, instead typing, when you want to use them.
4. Easy email forwarding (a nightmare with godaddy).
The only critique I have about Dynadot is their expired domain auctions. I won an expired domain auction on dynadot. I paid for the domain. Then they have let the previous owner pull it back and this happened at day 39 after expiry.
I really hate them for doing this.