In the past i extensevly used the rifle. I was pretty good with it close-combat. Now i have learned to love the sten.
FG42 is good only close up or long range if you are hidden so the enemy wont shoot you back. One big drawback is that it isnt silenced - enemy can hear where you are and return fire very fast
The rifle is good close up to a bit longer range than fg42, less bullets and slower shooting but the damage of bullets make it up or
very long range where the enemy cant see you.
But the sten - I love it, for very long range its great. Just keep moving and the enemy sniper wont hit you. Normal SMG-s are too inaccurate for you. Medium range is good too, just aim for the head, you might miss more but the damage it does to head makes it up very well. For close up, it isnt as good as other 2 but i have killed many medics with it, just burst fire and try to hit the head, it only does about 14-15 damage to body versus 40-50 to head so its very important.
And its silenced so often the enemy will get confused and cant hear where are you shooting from.
I like rifles, but i also like to move alot so sten is the choice for me.
If you want to take the FG42, better take the rifle and learn to click very fast