I think this is primarily going to come down to the method of cooking and the flavorings. I think it's unlikely that you can buy a microwave popcorn that will taste like the movie theatre.
You'll need a specific popcorn pan so that you can stir the popcorn continuously and that will also vent some of the steam from cooking (which a normal pot won't do. Whirley Pop seems to be a common solution here.
Next you'll need to find the right type of oil. Experiment with a couple of things to see what you like. Coconut oil seems to be commonly recommended (and not easy to find).
Finally you'll need flavoring. Try Flavacol. My work has popcorn on thursdays, and they use this flavoring. It's pretty dead on.
I don't think the actual pop corn kernels will make a ton of difference. It's more the cooking technique and other ingredients.
Here's my primary source, but further research and experience backs that up as pretty dead on.
I'll come out and say "no, you can't make microwave popcorn in a conventional oven."
For popcorn to pop, the kernel must reach a temperature well above boiling (which builds up steam, causing the kernel to explode). It must do so very quickly, otherwise the moisture will just slowly evaporate out, simply drying the kernel rather than popping it.
Microwave popcorn works because the microwave is primarily heating the kernels directly (because they contain the most water), and quickly. Air poppers don't use the oil, but they do get very hot, and the forced air heats the kernels very fast. And stovetop methods use the heat built up in the oil to heat the kernels quickly. Even fire-popped corn (a fun prospect) relies on fast heat.
Unfortunately, ovens are anything but fast. In the time it would take to heat the kernels, they would just dry out, and possibly start to burn the bag.
If you want popcorn without a microwave, stovetop popcorn is quite easy, and very tasty. I like using a wok, because it's shape is well suited for popcorn (sloped sides keep the kernels in the hot spot, while allowing popped kernels space to expand).
Best Answer
I have a theatre-style popcorn machine that lets the steam escape (ever so slightly) as the pot is overflowing. When I want to make a smaller batch, I do it the old-fashioned way: in a fully covered saucepan on the stove. When both are preheated properly, oiled and salted properly, it's hard to tell the difference. I do know this: a tightly covered pot will heat up more quickly (because it's retaining more heat), resulting in the kernels popping a little faster. That's simple science.
From the time the popcorn starts popping until it's removed from the heat, it's only a very short time. The average popped kernel is probably in that environment for a minute or less. Whatever steam the popcorn absorbs in the covered pan it quickly lets off when poured into the open bowl.
There might be a minor difference, but if you have to ask, you are probably better at making nearly perfect popcorn than anyone you're likely to ask. Getting the heat, oil, salt, and other flavorings right along with having fresh kernels of a variety that pops to your liking are going to have far more effect on the finished product than minor venting of heat and steam during the popping process. Once you have perfected the rest of the process, you'll be able to tell for yourself whether to cover tightly or not has much effect.
The great thing about figuring it out for yourself is all the popcorn you get to eat. :-)