One of the Foundations I find easiest to use is Dior Diorlight. It spreads very easily on the skin and doesn't look fake or cakey. The coverage is on the light side. It does have "light reflecting particles" but it doesn't look shimmery at all to me. It's difficult to recommend a colour, but I would guess 300.
We don't have Prescriptives where I live but I suppose BR means the Blue/Red family? If you think you are medium+ the lightest shade sounds too pale. Also, more yellow shades tones down red better. Foundation should always match your neck so there's no tell-tale lines. And doesn't the Flawless give you more coverage than you would want? I think their lightest foundation is Traceless. It doesn't come in their usual different colour families, just in levels of darkness like Level 1, Level 2 etc.