I've tried and liked i-dots okay--not bad, but not great.
Prior to my current WC Battlesights, I liked the Defoors best (I like a thin front sight), but it turns out I like the U-shaped rear notch and a TALLER front sight more (seems easier/faster to pick up).
I get a lot of crap for my preferred set up--I have the Vickers Wilson Combat Battlesights BUT I have a FIBER OPTIC in the front and a tritium in the rear.
My logic is that I like the STRAIGHT-EIGHT look during the day and even in dim light I can make out the front fine. I'd be fine with a painted dot but all they offer is all black and tritium rears. Vickers himself seemed displeased with my muddled miscegenation of his sights.
But in the DARK, I use a flashlight, so the outline of the front sight is there (even though I do have a little glowing dot in the rear).
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That said, I'm ALSO trying out the new Frank Proctor Y-Notch sights which have a VERY thin front and rear notch for accuracy, but it's FO and has angles opened up towards the top of the rear for speed.