These primers are all very different but great for different purposes.
MAC's Strobe Cream (link) looks best under foundation to give a light-from-within, pearlized glow. I also like to add a dab on my cheekbones on no-foundation days (which is pretty common for me, especially in the summer). Make sure you rub this cream into the skin for a more natural finish. I also own the full-sized version.
I pull out these "minis" - the Smashbox Photo Finish Primer (link) and the Makeup Forever HD Primer (link) - when I am wearing "full-on" makeup or want my makeup to be super long-lasting and flawless (i.e., for nights out). Both of these primers leave the skin feeling ultra-smooth, but I prefer the non-silicone MUFE option.
Last but certainly not least, the Clarins Beauty Flash Balm (link). I'm seriously considering purchasing a full size version! I regularly reach for this in the mornings and I do feel that it lives up to its claims - "instantly moisturizes, brightens, and tightens". Although it has a noticeable scent, surprisingly I don't mind it.
Do you like to use primers/bases?
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