come on, no one knows answer for my question?
Well one complication here is that there's no single answer to this question. Even in SC4 you couldn't always rely on 6K to get you out of trouble, as it was a high, so characters that pressure with a tech crouch get under it quite effectively.
In this game your main tools for setting pace are 6A, agA, 1K, 6K, 66K, throws, 3A, B6, and similar moves (obviously 3B when you've got the range). A lot of them aren't terribly safe, but they're the tools we're given that are fast. You might also be able to exploit 22_88A, 2_8B+K into SCH B, SBH's GI, the flapjack, and even the humble A+B, B string depending on circumstances. Also don't forget you can GI when you've got the meter.
What works for you will vary a great deal. If you're playing against a good stepper playing Phyrra who always stabs you under your horizontals, then 3A, 22_88A, and 1K are suddenly going to look a lot better than agA or 6A. If you're playing against Natsu at point blank, GI'ing or tick throwing off of 1K might be the only way to actually beat out what she's doing. But if everything she's doing is safe, odds are you aren't taking much in the way of guard damage just waiting.
6K is still good in certain circumstances, given it is a mid-hitting, tech-crouching, knockdown. But it's slower than it used to be and steppable. But you could take a step toward your enemy, making them think you're going to 6K or 66K, then hit 6A instead. Works on very reactionary players.
Who knows what you'll specifically need to use against whoever you're playing against. Just keep your options in mind and see what you can get done just by blocking and stepping.
