Connaught. They don't charge an arm and a leg for shipping or hyper-inflate the costs of all the European drug-store shave stuff I love to use, like Proraso and Tabac. It all depends what you like to use though!
Support your local bricks and mortar if you have one and they’re not trying to rip you off. Other than that, cut out the middleman and go direct to the manufacturer where ever possible. Simpson, Plisson, Shavemac, Timeless, Ralf Aust, Mike’s, Martin de Candre, Czech & Speake, Saponificio Varesino. These guys sell direct and will look after you. Often they will make you custom items and they are the best placed to answer questions.
The English Shaving Company is the one I buy from. They stock quality product, prices are decent and customer service is impeccable.
I tried several other vendors, they were all good but somehow I always go back to TESC.