LEDs go to 100% brightness instantly, unlike CFLs, which is very convenient for many applications (closets, corridor, garage, etc.).
But at this price point it's already about different convenience - not having to deal with replacement. Regular lamps go out and then you have to replace it, it's a hassle - stockpiling different nominations, opening fixtures, disposing old lamps. With LEDs you just put them in and forget about it. I basically replace all bulbs that go out with leds if fixture allows it because of this.
All the CFLs I have (except for 6 very very bad ones) go to full brightness instantly (or close enough that I can't tell the difference). (I use those bad ones in a bedroom fixture where the slow start is actually a feature. Made by Feit Electric - don't buy that brand.)
So if your CFLs are slow buy better ones. Walmart has good ones.
A CFL will last about 8,000 to 10,000 hours - I have to replace maybe 1 bulb a year in my house.
But at this price point it's already about different convenience - not having to deal with replacement. Regular lamps go out and then you have to replace it, it's a hassle - stockpiling different nominations, opening fixtures, disposing old lamps. With LEDs you just put them in and forget about it. I basically replace all bulbs that go out with leds if fixture allows it because of this.