I should have better phrased that. Reliability is also subjective. Lets put it this way, The Civic will cost MUCH less to own overall over a long period of time. As for reliability, you always take N/A over turbo. But rather then argue reliability, the cost of maintaining and overall life expetency with less costs, you just gotta give the nod to Honda. Less HP for most part means longer life. I don't imagine I'll be getting 200k miles out of my clutch or turbo, and perhaps not my engine. Under normal driving, I have to give the nod to The Civic SI. The odds are simply greater. the Speed 3 is just different. Now a regular Mazda 3, that's a different ball of wax. You cannot use the regular Mazda 3, and compare relaibility. They are really two totally different cars regarding reliability.
Example. For someone who is looking for a daily driver, and will be driving 25-30k miles a year with a lot of highway, if saving money is your goal, then the Civic is clearly the better choice. We all have to make sacrifices here. Of course the temptation to modify, and drive the car harder is ALWAYS there when you have high boost and that kind of torque with mod ability. Take it from an S2000 owner. My Speed 6 is much easier to go fast in. With a Civic SI, which is much like my S2000 engine wise, you have to rev it to go fast, so you just don't step on the gas and go. It feels like a normal car unless you really rev the stink out of it. The Speed 3 and 6, well they just GO, and overall that's gonna wear down the car faster, even under normal driving. It's opinion, so no need to argue.
I would take The Civic SI over my Speed 6 any day if you asked me which I think will hold up longer with less costs. The maintanence alone is far less as well, so you save $$$$$, but sacrifice performance. However, I knew that going in, and I'd rather have my Speed 6, even if it costs more to maintain, gets less MPG, and likely will not hold up as long. It's all a compromise any way you look at it when you buy any type of car. You gain something, lose something else.