Yamaha, Honda, Suzuki, Kawasaki, Husqvarna, Triumph, Ducati, BMW, KTM, Royal Enfield
You really can't go wrong with these big brands. Husqvarna isnt really big but they make some cool bikes.
Honestly Im riding around on my 1980 Suzuki GS750 and I still love it. I'd look for something cheap, 80s vintage if you dont mind a little upkeep and its great to learn how to take care and maintenance your bike. Butttt if you're looking for something thats not a sport bike Honda Rebels and Honda Nighthawks are really good choices. Browse around craigslist and you'll always find deals. I'm here if you have any other questions.