I have infinity, and I have reccomended them to many people on this board, and I don't think I've heard a single complaint from anyone who has installed them.
The only problem is that you want more bass. The largest speaker in the car is 5.25, and it is no where near large enough to good bass. What I suggest is replacing your rear speakers with JL stealthboxes. They are 8inch subs that are designed to fit into the factory space for the rear speakers.
Overall, this is my suggestion to you:
5.25" and 3.5" Infinity coxials for the kick panel and door. You should have to pay around $150 for all four. You could go for components, but the infinity coax has a rotating tweeter that will allow you to aim your highs, and since its already in the door, I would consider the more expensive system a waste of money unless you are a serious audiophile. For the rear, I suggest picking up some stealth boxes. I don't know what they cost or where they are available, only that they exist. I would estimate $150-200.
Now, we have satisfied your need for better speakers and more bass. Although not needed yet, bypassing the factory amp and adding a 6 channel amp will help even more.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>