What class in tf2 is the best/most powerful? including unlockable weapons

There is no single best class. It's just about preference and what suits a person the best.

I've seen some people play spy and be nearly unstoppable. I think spy is a cheap class, personally. I mean you get to be invisible and stab people in the back...how lame is that?

Likewise, some people master soldier and can rocket jump with unbelievable skill and ease. Learning to rocket jump with the best of them can make being soldier a very elite class. The ability to gain an aerial advantage is huge.

Medic is more about helping your team. Don't try or expect to get kills. Your main motive is to heal everyone and build up ubers that will enable powerful classes to be effective.

Engineers are also about helping the team, not about killing the enemy at least with a weapon. That being said, they build sentries which are really vital to protecting an area. A well placed sentry gun can make the other team's life hell. And they build teleporters to help the team.

A good scout can be really effective as well since they move so fast and are hard to hit even though they aren't super powerful.

Pyro is one of the easiest since you can just spam your flame and don't have to aim much. A Pyro can be really strong with the phlogistinator. Pyro is especially helpful in air blasting the opponent. You can knock ubered opponents off the point and split the ubered player from the medic which will limit the uber.

The heavy is a great class if you can get a medic to "pocket" you, which basically just means that the medic will heal and uber you only.

When I played, I mained demoman. Demoman are arguably capable of the most damage. You can set 4 or 5 sticky bombs near a sentry and take it out and of course cause damage to all classes.

Sniper is just like any other game. If you're good at sniping, you can kill a ton of people. Some maps/scenarios make it really difficult to snipe but a great sniper will usually find a way to make it work.

Again, the game is called Team Fortress for a reason. The game is meant to put the classes on somewhat of a level playing field and force people to operate as a team and maximize the potential of each class. A Pyro can spy check and set spies on fire preventing your team from getting stabbed. As a result, the demo or heavy can keep attacking. Meanwhile, the engineer can build sentries, dispensers, and teleporters to assist the team. The medic can heal and uber. The scout can distract the other team or even the sentry which will allow a damage class to take out the sentry.

You really just have to try the classes and watch other people and see what works best for you. And try out different weapons.

Holy shit, TF2 ruled my life as a teen (that and S4 League), until it became f2p.

My favorite class was always engie. I loved figuring out which corner to set up that gives spies a hard time while effectively depending the base; especially when I can set up camp on the enemy's side. Such proud moments when the other team yells at me and rage quit over how well I placed my sentries lol, or when 2 - 3 people change to spy just to take me out lol, or that one annoyingly skilled Demo that hunts me down. However, like LionsMane said, it depends on your preference. Engie requires patience and planning, while other classes play differently.

I'd argue spy. It's basically no longer an FPS when you play spy, because you're no longer playing against other classes. You're playing against the players.

You spend most of your time not shooting anyone, just walking around and blending in. . .till you don't. You don't even need to even kill anyone, just be very distracting to derail the whole game for the other team.

The other classes have their strengths, but nobody can change the game like a well placed spy. That's not even counting for all the goods they give you.

It's more fun, in my opinion to drive 3 players to Pyro rage for the rest of a game and be way less effective as a result than just to play it like an FPS. After all, that's what the rest of the classes are for.