> your opinion as to why the D3xxx series is your personal favorite.
Thanks for the request, and the opportunity as to why ....
Simply put, I'm a fan of the Bauhaus principle that "less is more", a maxim that can/could be applied to many aspects of our lives.
Firstly regarding size, the D5100 is marginally larger, by a few mm only, in each dimension (LXWXD) than the D3100.
Second, having used the D60 as my first DSLR, after 8 years of CoolPixes (990, 995 and 4500), the improvement in resolution (ie the D60) was noticeable, but the the image composition was unchanged, except the move from 4:3 to 3:2. Many fine pix were produced with the tiny, finger-nail size sensors in the CoolPixes.
I sorta agree with Ken Rockwell that 6-10MP on a APS-C size sensor is more than enough to produce excellent repro at 30"x20".
As to form factor, I've argued here before that the small form factor of the D3XXX series (and its precursors) is an advantage to all but the very large-handed person, for whom a D7XXX series may be big enough with its increased dimensions compared to the D3XXX series.
As to back buttons, to each his or her own. I'm familiar with the D60/D3XXX series physical setup, and in fact, found the D5100 setup less comfortable, but to each his/her own. The movable screen on the D5XXXs are an advantage, one that I had with the split body CoolPixes, but the rearrangment of buttons on the D5XXX series I found a bit clunky.
Lenses always seemed more important to me than sensors and their "MegaPixiCalityNess", so I've acquired good quality lenses (some secondhand) to complement my bodies, sometimes buying FX lenses to get the so-called sweet spot when used with DX format.
My most used lenses are: 12-24/f4 (DX), 24-85 AF-S (FX), 35/f1.8 (DX).
Six months ago I was asked to shoot the Australian National track cycling championships by the coach of a group of young Korean cyclists who were training in my home city of Adelaide, Australia.
Not having shot high speed sport for years, and not having a fast mid-range zoom, I hired a Sigma 70-200/f2.8 zoom, not stabilised as the current version is, and went to work.
I managed to get some good, sharp high-speed action shots in an arena that was notoriously underlit and with mixed lighting circumstances.
As much as my commission was to document the event for the Koren Cycling Federation, I also wished to be able to show that an "amateur", "consumer" DSLR body can get very acceptable results, while all around me were professional photogs with Canon Mk5DII and D3 Nikons.
The two pix below are first an inadvertant shot of the velodrome ceiling, taken accidentally as I hoiked the 1.5kg Sigma lens, attached to the 500g D3100 body from waist to eye level. This has been printed for the client at 30"X20" (75X50cm).
And second, a panning shot of SungHoon Park travelling at 70 km/hour (45mph) which is sharp and a realistic rendition of the colour sources in play at the time.
Both photos are straight off the card, no PShop, no nuttin'.
That's my story, and to reiterate, the gear these days is always good enough, it's what we do with it.