Agreed, I was looking at the new 308 and the new Mazda 3 a few months back. Went and test-drove both the cars at least 3 times before making the decision.

As the 308 will be pretty much the same as the 408, my observations:-
- 308 interior is very very nice. Is very plush and feels very premium. I don't think there is any other car in this class that can match it
- Mazda 3 interior, although feeling cheaper, is much more intuitive and user friendly. I'm not a big fan of the 308 touch-screen
- NVH quality of the 308 is fantastic. Miles ahead of any competition. But the Mazda 3 is still a more of a drivers car
- Not concern to me, but may be issue to most is the back-seat. 308 is much more comfortable place and Mazda 3 which is a little cramp
- Ease of ownership - I'm still worried about reliability of 308 especially the Turbo and its additional stress. However, Mazda 3 also has a very new technology in its SkyActiv engine. Questions on carbon build-up or future problems is still there - but so far have not come across anything.
- Tech, personally, I'm a bigger fan of Mazda 3 High Spec with the Blind spot monitoring, lane watch and city brake. The 308 has adaptive cruise control but unfortunately no blind spot monitoring.

Also was thinking of the CX3 and whether to wait for it. Size is not an issue for me as we do not have kids and only passenger is my dog. So please consider size for your own fit.

But CX3 was crossed out because (i) no Activsense, especially for the price and (ii) the dash and center console feels very cheap like the Mazda 2. Mazda 3 is only slightly better

In the end, we picked the Mazda 3 based on following list of priorities
1. Safety including NCAP and IIHS results
2. Reliability (or perceived reliability)

Even if rechoosing today, CX3 will still totally be off the list as no Activsence for the price being charged. It will still be a close match between 308 and Mazda 3.