If you are running a message board, I would suggest looking for the following: PHP support, MySQL database (you will need at least one database for your forum), FTP account (at least one). A typical forum will need no more than 50MB to start. For a free forum, look into phpBB. A good paid forum is vBulletin.
As far as disk space and bandwidth: I would be weary of going with a host that promises 300GB of disk space and 3TB of bandwidth for $7/month. This amount of disk space and bandwidth cannot be provided for that amount even at cost, so it's likely that if you get anywhere near those limits, your account will be suspended for "server resource overuse". The higher a host oversells, the less resources each client is permitted to use. 300GB disk space and 3TB of bandwidth, if used entirely, could easily bring an enterprise-level server to its knees. They are likely cramming hundreds of these accounts onto a single server. Overselling isn't bad in itself, but when they oversell to the point where they could never deliver what they promise in reality- that's bad. 300GB disk space and 3TB bandwidth for $7 is pushing reality.
So instead of going with whoever offers the most disk space and bandwidth, go with a host that offers plans that fit your needs. Just remember: You always get what you pay for. $7 will never get you 300GB/3TB.
If I were you, I would add KnownHost to my list of hosts to consider.
Shared or Reseller Hosting, no setup fees :: KnownHost LLC
They offer reasonably priced hosting packages (they don't do massive overselling), and they have an awesome support team. They also have plenty of positive reviews (see webhostingtalk.com). You also have a clear upgrade path (VPS and Hybrid Servers), so when your site grows, you can easily upgrade. They also offer cPanel and Fantastico with all of their plans, which are great features. And they will support a number of message boards (PHP and MySQL).