I'm a fan of aluminum. Lighter = Faster
Look on craigslist for some garage steals. You can find some good quality bikes on there for a lot cheaper then a new department store bike. Good welds and good brakes are the thing to look for. The style of bike totally depends on you.
You have to ask yourself :
- Whats my style? (cruiser or MT. Bike)
- What am I looking to do? (on-road or off-road)
- How am I planning to ride? (cruise or go fast)
I have both a Mt. bike and a cruiser and I like them both. Each bike has its advantages and disadvantages. If I started all over, I wouldn't do anything different. I say build one, then build the other.