Agree with the above ^^^ posts...
If you have one car, and drive more than 10,000 miles a year, and are on a budget the zhp 330i makes a lot of sense.... esp the 4 door, imo the only e46 coupe that looked really awesome was the M3.
When I bought my e90 330i (sport, stick) over 4 yrs ago, I was going back and forth between e90 335i, e46 M3, e46 zhp sedan and of course the e90 330i. Since at the time I was doing about 20,000 miles a year, and didn't want to put crazy miles on an M3, especially since they have a couple very common expensive issues- some of which are catastrophic such as the crank bearings, vanos, and rear subframe issues I ruled out the M3. At the time, the 335i was still pretty new and the thought of BMW's first turbo effort in years scared me. That left me with the e46 and e90 330i... I found the car I bought for an absolutely smoking deal and I got it. First car I have ever owned that I didn't get bored with after a year or two. Sure, I have put some money into mods to make it quicker, better handling and more fun, but the car has been very very reliable. The only non maintenance or non mod money I had to shell out as a surprise problem was a starter at 60k miles (really?!) and a folding mirror motor. Now with 132,000 miles it still blows me away every time I drive it. Do I want an M3 (or a cayman s or a z06 or...) sure I do, but when I drive it, I don't think about buying another car. Going to work, the grocery store or at the track, the car just spoils me. It feels great, it's just always on my side. Being paid for helps too
IMO, sell the 328, and if you drive around 10k miles a year and can afford a surprise here and there get the M3, if you are on a budget and drive more miles/yr get the 330i.
EDIT- the other rub about the e46 M3, for me at least, is that no matter how much I love those cars in stock for, I would have to put serious money into mods... I would prefer a comp pkg car since they are of course newer and have the convertible floorpan that helps with the subframe issue and the quicker steering rack, but they don't have cruise control, which is effing absurd, so there's money there to make that happen. Then, I would have to get a set of euro headers/cats for some extra hp and way better exhaust sound. And finally there is absolutely no way on earth. I could avoid getting a csl rep intake (evolve?) and tune, as well as a set of coilovers... I mean, how could I possibly live with an e46 m3 without those must have mods ? Haha, I'm such an asshole, never happy.
Good luck whatever way you go and post lots of pics!!