its up to you. there are many good options. zacuto, cavision, cinevate, redrock, indifocus... nearly ALL of them make both rails and boxes. all are decent, some are awesome.
personally i will never part with my zacuto baseplate and rails...
THANKS WGZN for your answer yuh zacuto is too expensive for me although it is very nice i need something cheap so thinking of cavision or cinecity rails.I just found out a new Canadian Company "SHAPE WLB" they seems like pretty good rigs i can use em as a rail system for my 35mm cinemek adapter and mattebox or shoulder mount steadicam so it has multi uses and they are not too expensive
ive seen their stuff (or similar) on that douchebag "ghost adventurers" TV show.
it looks pretty good and id assume it works. but if that were my only reference, id consider the source dubious...