Everyone has an opinion, this is mine. At $300 for a new bike, road, mountain, hybrid, etc, the best you can do is a mass market big box bike with substandard components.
That same $300 can but you a quality used middle of the line brand name bike, like those you mentioned. Sure, the bike may be a few years old but if it was quality built when new and reasonably maintained it is still a quality bike with better design, materials and components. When you're shopping for used, be looking for those bikes that were purchased by individuals who gave up riding after a few months or upgraded shortly after that first purchase. A good quality bike will be serviceable for years if properly maintained so even a well used quality bike is still a much better bet than anything you'll find at the big box stores at that price.
Stick with bikes from Trek, Specialized, Giant, Cannondale, etc., and they'll serve you well until you're ready to up-grade to a newer one. My recommendation would be a cyclo-cross bike from any of those manufacturers... a great choice for all around riding.
That same $300 can but you a quality used middle of the line brand name bike, like those you mentioned. Sure, the bike may be a few years old but if it was quality built when new and reasonably maintained it is still a quality bike with better design, materials and components. When you're shopping for used, be looking for those bikes that were purchased by individuals who gave up riding after a few months or upgraded shortly after that first purchase. A good quality bike will be serviceable for years if properly maintained so even a well used quality bike is still a much better bet than anything you'll find at the big box stores at that price.
Stick with bikes from Trek, Specialized, Giant, Cannondale, etc., and they'll serve you well until you're ready to up-grade to a newer one. My recommendation would be a cyclo-cross bike from any of those manufacturers... a great choice for all around riding.