There is a famous sig around here that goes something like:
There is no best host, there is only the host that is best for you.
For starters what type of control panel do you want, do you want the host to support your clients to, what country are you located in, what is your target market, what type of bandwidth and space requirements are you looking for, and what type of support do you need?
The list goes on from there but that's a good start in picking a host.
justadollarhostin is right, you have to be sure about your needs and budget, then you can search this site for a good host for you.
If you are just looking for reviews to find a reputable hosts, I can tell you I'm with hostgator and eagerhost, and they have been great for me. I'm also planning to use ResellerZoom very soon, I have heard very good comments about them here.
I would always perfer the site having best support all time support, whome i can chat online incase of sales or support. Why?
Its simple when you become a reseller their are many times when you want the reply very fast you can you have a chat with your partent company to reply to all your customers Q's. Lets say your client asks you what it will cost for extra bandwidth and you are not sure for cost price what you will do Will you ask your client to wait till you get the respond from your parten firm?
Also i would perfer a company that gives me rights to create resellers from my reseler account itself. Help me to set up offer best supportand in time support maintaining low cost like $10/1gb with reseller rights.
If you are looking for reseller plan besure you are in safe hands test your hosting company.