What is the best domain reseller programs around.
Thanks in advance

How long is a piece of string?

Hey thanks for your kind words today.

As always: it depends on your requirements. Want WHMCS integration? Look at the resellers they support. Have a WHMCS license? Might try their free accounts. Unsupported resellers might have their own WHMCS modules. Are you looking for best price? How much are you willing/able to pay upfront? Actually, there are too many unknowns to give you a simple answer.

IMO, there is never a "best domain reseller program" or a "best provider" etc., however you need to find the best one for you.

There are good reseller plans available from all the leading Registrars in the market, but somehow Resellerclub seems to stand out from my perspective (but that is just my personal opinion).

A search in WHT of previous threads, might help too. Here's what I found:

http://www.webhostingtalk.com/showthread.php?t=906490
http://www.webhostingtalk.com/showthread.php?t=906312
http://www.webhostingtalk.com/showthread.php?t=905629

Lastly, try google "registrar compare"

I'm using ENOM for their API functions and fast registration but they are not the cheapest.

You should must be specific about your own requirements first because features and services offers by your domain reseller must be compilable with your requirements. If you are planning to an ecommerce website. It may require a member panel and live chat features for maintaining healthy relationship with your client.

eNom are the biggest reseller. How do you think they got there? Control Panel pretty good, good API. What more do you want?

eNom are the biggest reseller.
What do you exactly mean by that? Revenue, registered domains, number of resellers,...? And where would you get the relevant data from?

See their website. Biggest Revenue, domains, and resellers.