In my wandering around the Internet I have occasionally looked for and found (in a limited fashion) comparison photos of various miniature ranges from different sources. The eternal justification of all those boxes of miniatures that we have all been hoarding, trying to find a use for them. A reason to warrant buying a new game because, well you already have a load of miniatures that you could proxy into the game (honestly).
So below is a long shot of a range of miniatures from a select source of different games that I presently have. Starting from the left and working right;
1-2 Terminator Genysis, 3 Zombicide, 4-5 Project Z , 6-7 Mars Attack, 8-9 Deadzone, 10 Imperial Assault, 11-12 AVP, and for comparison sake 13-14 Warhammer 40k
Some closer photos of the line up
Continuing on with the photos,from left too right again we have; 1-2 Zombicide, 3-8 Castle Ravenloft, 9 Descent 2nd Edition, 10-12 Arena of the Planeswalkers.
and again some close up photos for better comparison
In all I would wholeheartedly endorse using Zombicide figures alongside Project Z, Mars Attack and Deadzone. Terminator Genysis are ever so slightly smaller, so really will not make a huge difference and at the other end the AVP figures are just starting to look a little tall compared too the rest.
As far as the fantasy figures go, all of the ones on the photo could be used alongside any of the others without any issue, although the Descent ones appear to be overall a little bit on the skinny side.
One range of figures which I did not include in these photos were my Frostgrave Soldiers and Cultists, I found that these figures were closer to 25mm end of the spectrum and overall looked more stocky when compared to the others, giving them a slightly cartoon look (This is not a bad thing and in my opinion suits the feel of Frostgrave).
One thing of note is the Castle Ravenloft and Temple of Elemental Evil miniatures use the same style and suit each other well, even though there are a few years between them which did concern me as I think that their miniatures are from different ranges.
Fortunately the Imperial Assault figures even though produced by Fantasy Flight have a more realistic look too them that the ones in Descent, so do not appear flimsy.