best web site/variety of paints

well,,,,I think GreatModels, Squadron and the Internet Hobbies......There are dozens of sites out their and it really boils down to what you prefer.  But, I've had really good luck with the shops that I mentioned.

Relying on one source is convenient but not necessarily prudent. A little shopping around can yield you better pricing and quality of service.

Be a educated consumer: check for product availablity (is it real time or updated periodically do they have what you want when you want it), compare pricing, shipping costs and delivery times.  Some might sell it a bit cheaper but in the end you pay hgher shipping fees thus negating the difference. Go for the best overall service and experience. 

Check SprueBrothers. 

Everyone has their own favorite... 

Gerald  is right.

but to answer the raw question  who has the biggest variety

i just checked  and squadron offers 1724 items  great model offers 2490 items

I like Tower Hobbies, they cary all the water based paints I use, Floquil, Polly S, Model Master Acryl and Tamiya. One of the things I like is they actually carry the full line of Model Master Acryl, the MM Fantasy and Naval colors are hard for me to find elsewhere.

They are a good general purpose seller, they carry tools, stock styrene plastic and a good variety of kits (autos, planes, armor, ships etc) so its easy to do a lot of shopping in one place. Not so great for more obscure items like Eastern European kits or resin, but really good for the basic stuff. They are very fast too, I usually have my stuff within 3-5 days of placing my order.