seeds Any tips, tricks, or hints for picking the best seedlings?

So in my setup I have 2 solo cups of each variety with 2 seeds each (about 12 varieties). I'm still waiting for a couple varieties to break ground but overall I am having good germination rates of 2+ seeds per variety. My goal is to have one plant of each variety to put into a 5 gal pot and move outside.

How do I pick the best seedling and when do I cull one when there are 2 in a single cup? Is it always the first one to germinate or are there other factors? All still have their seed leaves and haven't developed the 2nd set yet.

I think the goal is to get to one seedling per cup (hopefully with 2 cups per variety) which I can grow out for a pretty long time before choosing the strongest plant to move into 1-2 gal pots or straight to 5 gal pots

I will post some pics when I get home this evening. In the mean time I appreciate the advice!

In my opinion is better to grow a few plants of a single variety than to grow 1 of each. Having 1 plant per variety can be a tragedy if you screw something up or a pest attacks it you kiss all your hopes and dreams of the pepper goodbye. Or if you end up really liking one variety but only getting 20 or so peppers from a plant then you will be sad because you can't make very much sauce or flakes from that few of peppers.
 
Just guess by size of leaves / stem, bigger is better. you can wait till they have a couple more leaves, they won't crowd out of a solo cup too quickly.

word. I lost my only Bolivian Rainbow to aphid attack. But, I have plenty more pepper plants! Just no Rainbow.

There's usually a runt ... but wait for some true leaves. I've had first sprouters languish while late comers put them to shame. If they both look good, I often try to figure out a way to keep 'em.
 
One thing I can't stand are runts. I used to baby them along, thinking they'll surely catch up and do great. Come June they're still runts and will never be good producers. PURGE!

Will 2 plants per variety be too much for a 5 gallon bucket/root pouch if I try to keep the two strongest?

Would 7 or 10 gal be better suited for 2 plants? Are there any other issues with having them too close together? Outside of competing for nutrients and root space, which wouldn't be a problem with a big enough pot.