I'm pretty inexperienced also but I'd make the suggestion to consider a used bike. Many people sell 12 month old bikes in great condition when they realise they're not going to use them like they thought they would. Also, being your first bike you reduce the risk of a wasted investment and you can always upgrade later. For $450 you might pick up an $800 bike (when new).

I can't speak to the bikes you've listed but there are a lot of "help me decide" threads here which will cover them for sure.

Many recommend visiting some of the bike stores in your area and having a chat to the team there, understand the options, work out what size suits you and what features are important. If you're up-front about your budget and a inclination to get a pre-loved bike you'll also determine how willing they are to see you become a lifetime customer. You might not be buying a bike from them but surely you'll need equipment, parts, consumables and servicing over the life of the bike. If they treat you well you'll be back.

Good luck with your research and purchase.