I can comment on the 70-300 non-L and L versions because I had one and have the other.
The non-L was good for what it was, a 70-200 IS USM for a lot less than the 70-200 f/4 L non-IS (at the time, now they're equal in price). AF was good, IS was good, even IQ was ok up to 200mm. But in the 200-300mm range, where I wanted it most, the lens just fell apart.
So I ditched it and got the 70-300L. Couldn't be happier. Compared to the 100-400L it's better and newer, and cheaper (now, although at the time they were equal). I could carry it all day (and often do) on my 7D, it's one of those "the lens is an extension of my eyes" things, where it just works without me even noticing. According to test charts and whatnot it's sharper at the 70mm end and still falls off a bit at 300mm, but I honestly can't tell the difference, to me it's sharp everywhere (maybe my 7D sensor doesn't stress it enough).

As for the 100L macro, that's also a wonderful lens by all accounts but I've never used one. What I can tell you is that the 70-300L and a set of Kenko Extension Tubes also makes a very nice occasional-macro setup. IS is only 'regular' not 'hybrid', and for macro you really should MF anyway when using a slow zoom lens on tubes (I presume AF on a real macro lens like the 100L you can leave on when 'in the field', still use MF in the studio), but besides that you still get the great IQ using the zoom on tubes.

I'd say the real decision is yours, Macro (and a nice Portrait lens), or 300mm built like a tank for Wildlife?