Much more difficult.
As long as you're not storing your ingredients in open sunlight - and why would you be? - it doesn't really matter what color you get. A little indirect sun isn't going to do any harm to the contents of a dark bottle, never mind indoor lighting.
I suspect all of mine have the polyseal caps (at least, the caps all have plastic cones inside, so I assume that's the same thing). They seem to do the job, and you don't have a little paper/plastic/foam gasket falling out of the lid after a while.