Hi,
I'm a new comer and firstly thanks all posters for your fruitful comments here.
As your list is similar to mine and so just want to share my experience as I just bought AX5Ai+3910 (bought 2 mths ago). I did several rounds of listening against:
1. Denon 3805
2. Yamaha RX2500
3. Pioneer 2014i & AX5Ai
The reasons for AX5Ai:
Features:
1. For me, sound comes first so 3910. But it wastes your $ for 3805 to buy the Denon decoder twice.
2. I-Link and USB.
3. Bi-amp.
4. More quality-built, e.g. plug, speaker plug, case, etc.
Sounds:
1. Open sound field, much better than 3805 and the same with 2500. 2014 is more open but less stable.
2. Mid & Bass control, much better than 2500 & 2014 and the same with 3805.
Testing software:
1. Eagles - Hotel Califonia Live
2. Dire Stratis
3. Some Chinese vocals (I'm a Chinese)
4. Wilson Audio Test CD (a serious of pin-point drum)