Personally I do not like Weaver freight cars. There is just something about them that turns me off. I think that some of them are well detailed and some are not, and I do not like plastic trucks. I also think that I should not have to add weight to a car once I purchased it. Now the last Weaver car I purchased was back a few years ago so things may have changed. I do like Weaver engines, and I really like the new steam engines that they are producing now.
All in all, it is what you like and what you want to run.