Well, kind of an easy question with several answers. If you want a Merkava 1, Tamiya's kit is your only choice. Just saw one marked at $20 at my local store (I helped a mom pick it out for her son going to an 11 yr old's birthday). This is a decent kit and is well engineered like most Tamiya kits. Has some motorization holes, but easily taken care of.
If you want a Merkava 2 or 3, then get Academy's kits. They come in a few variations, enhanced ones come with the little metal balls & chains used to defeat RPG rounds. Some come with mine rollers. Trumpeter makes a bad copy of this kit that is to be avoided. Academy kits are very good.
The only DML Israeli tanks made are the M50 and M51 Super Sherman and Isherman.