I'm considering issues of scale. My favorite scale is 28mm. I love the balance between detail and size. There are a lot of manufacturers out there for all periods/genres. The only real drawback, from my standpoint, is cost. Other than that, this is the sweet spot for me.
The two other scales I'm willing to consider are 20mm and 15mm. There are a ton of minis for all historical periods as well as fantasy and sci/fi, available in both. Honestly, I'm not even looking for fantasy in anything but 28mm. It's when looking at historicals and sci/fi that I have to give this some thought.
The largest WWII mini game is played in 15mm. I think, for my purposes, WWII will be 15mm and 28mm. I'll have to decide if I'm actually going to play Flames of War before I buy any more 15mm stuff. There are several promising sets of rules for platoon or lower combat that would be great with 28mm.
Looking at other historical periods, ancients, medieval, Napoleonic, ACW, I can see the attraction of giant armies in those periods, I'm just left cold by the models. I have several blogs in my blog roll from players who game in those systems. I'm trying to find the attraction for them but I just am not seeing it yet.
So, where does 20mm come in? Modern and Sci/fi. There a ton of nice model makers out there working in 20mm. Nice vehicles, good infantry, nice terrain.
Here's the thing. I don't really care about collecting different scales in and of itself. That's not the issue. I have every intention of collecting WWII in both 28mm and 15mm. It's the terrain that causes me issues. I love terrain and want my tables to look great. That means a lot of stuff, because let's face it, people don't normally fight over empty ground.
If I buy the, really tempting, stuff in 20mm, then that is a whole different set of terrain I need to collect as well, and that is what makes me hesitate. So, if anyone can tell me what they love about 15mm as well as reasons to take the plunge on 20mm, I'd appreciate hearing it. I'm still early in my collecting so I have not committed myself to anything.