There isn't a map editor better than the other one. Each one has his own good and bad characteristics and you have to choose the one that you use better. MTA map editor is very good for newbies and I think that it's the best way for starting mapping but the problems here are that it doesn't have samp object and so you can't put them in your map if you use MTA map editor unless you mod it but it's a bit annoying. (If you want to download that, just search on ******. You'll download the mta client and, once you have opened it, you have to go to "map editor")
So, if you want to use samp object I suggest you Samp Map Editor. Maybe for the first times it's harder to use than the MTA Map Editor but it's very good and maybe mapping it's faster on the SAMP map editor than the MTA one.