I'd choose the Sony a300. It has anti-shake/"super steady shot" tech in the body so every - that is every single pea-pickin' lens used - is anti-shake. From primes/normal lenses to macro lenses to tele-zooms to super-zooms - every single lens. So, your 85mm f1.4 (already pretty fast) Carl Zeiss lens is also anti-shake allowing for better low-light performance. Nice.....
I agree with the need for a solid system - it's frustrating when you're trying to find something and discover it's simply not available.... as in, "where are those Sony T/S lenses again? Ohhhh, we don't have those...." Arrghhhhh!
However, with a photographic system there are MANY variables to consider. Not the least of which is availability of a good selection of camera bodies, lenses, and flash-guns.
Fortunately, all of the 5 major manufacturers Canon, Nikon, Olympus, Pentax, and Sony(Minolta!!!!), CURRENTLY have adequate lens selections and most have adequate flash-gun options.
I use "adequate" b/c, honestly, how many people are really going to buy a 600mm f4 super-telephoto or a 24mm Tilt/Shift lens or a 16mm fish-eye? Seriously?
Yea, not many.
How many people will buy a "standard" zoom or a 70-300mm - nearly all. In fact, some of those people may even eventually buy a fast 24-70mm or 70-200mm and some fixed-focal length "gems" (be they macro/wide/portrait/tele). Which company offers those kinds of lenses? Yup, all of them.
My point is that most photographers lens needs are already present in the Big 5 line-ups.
For flash-gun needs, again most photographers needs are met in the Big 5 line-ups - though Canon and Nikon are light-years ahead.. ;D
So, how much lens/flash-gun over-lap is necessary to say a system is "adequate"?
This is why i think the Holy Grail "Whole-System" argument is not as thoroughly valid as it once was simply b/c MOST photographers NEEDS are met and all the Big 5 are expanding their line-ups.
Anyway, i believe every one of the Big 5 manufacturers offer some incredible camera value today and for not a lot of money.
Which one is "best" for you depends on your personal handling preferences.