Since you want a main battle tank, the term generally refers to a modern tank (WW2 tanks were classified as light, medium and heavy). Many of the available MBTs are relatively simple kits with one piece tracks and side skirts that cover most of the suspension.
While I often tell people to avoid buying a kit because of its brand name (i.e. Tamiya over Dragon, etc.), Tamiya does have many modern MBTs, probably a more extensive line than any other single brand. They make an excellent German Leopard 2A5/6, French Leclerc, JGSDF Type 90, British Challenger II and a decent M1A1/A2 Abrams, not the best, but a solid kit that is easy to build. They also do an early IDF Merkava.
Dragon has the top Abrams kit (the ultra late M1A1AIM and M1A2SEP), but are more comprehensive builds. As an experienced modeler, they should be of little problem to you, but the kits are highly sought after and have climbed in price to the $60+ range.
The Tamiya kits I mentioned are readily available, can be found for much less than retail price and are all good kits for the first time armor builder.
Another modern MBT that may end up in the news more is the Israeli Merkava 4. There are two kits by Academy and Hobby Boss. You can check out reviews of either kit. The HB one has a misaligned suspension system that purists cannot live with, but the vast majority of casual model builders would never notice.