I can also vouch for sayno2drugs (from cali)! I have had carts from MJ and Sn2D. MJ's carts are very good! I believe that MJ's are filled with distillate but Sn2D have Cali branded carts (distillates, CO2 Extract, resin). I have tried a few and for me the 22k brand seems to be the best that Sn2D offers. (the Karvana carts always seem to clog)
If you are buying from the UK I would stick to MJ's carts because you will not have to worry about customs and he is a fantastic vendor and very quick to deliver. Happy vaping!!!!