I have both the AFV Club and the Academy M 10 kits and have to say the Academy kit is my favorite. It is not without problems, however.

First off, for some stupid reason it has bunches of knock-out pin holes on the inside surfaces of the turret -- I would strongly suggest filling these before assembling the turret. I was lucky and had a hole punch of the correct size, so I filled the holes with stryrene disks and a bit of putty.

Also, the raised outlines of the tools on the rear hull should be sanded off -- otherwise they will show after assembly.

The lower hull interior is really nice right out of the box, but again, the turret stowage is a little off, compared to references I have. Almost all the parts are in the kit, however, and you can check their placement against photos of the real thing, here:
http://www.kithobbyist.com/AFVInteriors/m10/m10a.html

Some people say the AFV Club kit has a more correct turret, but I'm not convinced. I think the AFV Club turret is too wide and the Academy turret is a tad too narrow. The turret counterweights on the Academy kit look a little off, too.

One thing that the kit gives you, but the instructions do not tell you to use are the U-shaped brackets that hold the pivoting support "spikes" on the turret top. The kit has them molded on the front part of the turret, but you must shave the U-brackets from the accessory sprue and place them on the rear part of the turret yourself using reference photos.

You get lots of extra goodies in the Academy kit, including and entire extra set of road wheels, a great accessory sprue, plus some super numbers, letters, casting marks, boltheads, wingnuts, etc., that can be used on any of your U.S. vehicles.

One last pot-shot at the AFV Club kit -- curiously, there are no ammo rounds provided for the turret racks. The Academy kit has them and they look pretty good.