Machu-
This is my personal opinion, so please take that into account... others here are bound to have a different order.
Tamiya - (Newer releases that is)
Kits that I have personal experience with that I would HIGHLY recommend are:
Wespe - Superb, well detailed and easy to build - looks great OOTB. Nice rubberband style tracks that actually look the part and are gluable.
Marder III and Marder IIIM - See above... Great Kits!!
PzKpfw IIIL - Really fun to build and looks great OOTB!
StuG III (Early version - the one that doesn't come with side skirts) - Again, easy build and looks great without the aftermarket stuff.
Any of their Panther G's (Early, Late, or Steel Wheel)
Any of their newer Tigers (Initial, Early, Mid, or Late)
I have heard that their King Tigers are good as well, however I hve no experience with any of them.
Dragon/DML - These have a few more cleaning up issues, and the molding doesn't seem to be as crisp as the new Tamiya stuff.... but they are a whole lot cheaper and are well worth the money - good kits are:
StuG III - any one of 'em. Some minor difficulty to get assembled correctly - but not crazy....
Panther A (early, late) - Super kits that rival Tamiya's G's
Panther D - see above - great kit
Italeri - I generally don't build these if I can help it. They do offer a large selection of softskins though... Others seem to love Italeri - so get one and see what you think?
Academy - I only bought one kit - the old PzKpfw IV H (copy of Tamiya's old H) - it pretty much didn't do me any good.... I have heard that their newer stuff is pretty good, so maybe I'll get a new one and see what's shakin'
Alan - UUuugh, the dudes that cut steel for the molds must be heavy drinkers.... Don't expect anything to fit properly. Don't expect the locating pins to line up with the holes they go into. Don't expect to be able to get the model built if you follow the directions in the order that they say in the instructions. I speak from experience - I am building their BIson II now... i've already used half a tube of Squadron putty. The gun carriage doesn't fit into the fighting compartment, and of course I've already glued the top hull to the bottom (just like the instructions told me to)...... anyway - i should quit now....
Others should be able to help you more with Allied kits - I have no idea there
Jeff