IMO Sig's best range from opponent is between his 1K's tip & 2A's tip. At 1K's tip range Sig has more room for using K & back stepping then punish counter most characters BB & other quick short reactions from opponent. It similar to quick whiff punishing in tekken where the dodger evades the attacker's 1st move & counters the attacker's 2nd string move. Like Sig Ks Mitsu's G at tip range, Sig backsteps & evades mitsu's 1st B of BB, then Sig 6Ks Mitsu's 2nd B of BB. This is still experimental & might fail depending on opponent's time & choice reactions vs Sig's timing & confirm. After tip range K vs G Sig can backstep & backstep more with 4B+K, or simple 4B+K'A+B after K. It also depends on the opponent's character range.
4B+K'A+B is good for regaining space while whiff punishing, it can be used often from most attacks at tip range. Another set up example: Sig 1Ks & normal hits opponent, Sig ends in disadvantage & opponent BBs, Sig GIs opponent's BB, the GI might force your opponent to do a slower attack or throw to counter Sig's GI, that might allow Sig to do 4B+K'A+B after normal hitting with 1K.
IMO Sig's best poke mix starter is 1K or 2A, why? pretty simple, neutral G: after Sig Gs vs opponent's disadvantage but safe attacks, it gives advantage to Sig, if the opponent is smart she/he will G, if the opponent is not smart or is reckless she/he will attack at disadvantage, but regardless of opponent's choice Sig's 1K is very likely to hit, more likely than mids. 1K is low damage but is good for leading or luring reaction like TJs & LowGrd. 1K (i15) on counter hit gives Sig +2 for an i13~1K, that means that after counter hitting with 1K, Sig can interrupt most i14~2As, Sig can 1K,1K,1K... against 2A friendly opponents.
Sig can 1K for an i12~6K against opponent who tries i12 or i13 moves to trade/interrupt, but another 1K after counter hitting with 1K still has more chances to hit or counter hit. If the opponent is clever she/he will might try 2G, 3GI or TJ. if opponent G2, Sig gets WS'K, B or 4K. If opponent 3GIs, Sig gets 11_77A. If opponent TJs, Sig gets 6K or 6A for right RO.
b6 & 2A are good tools together at tip range. Set Up: b6 hits tip range, 2A counter hits at tip range, 4B+K'A+B hits if opponent reacts with quick short attacks, that might promote opponent to use a slower range attack next time. Mix Up: b6 hits at tip range, 2A counter hits at tip range, opponent tries slower range attack, Sig 6K, 6A (if opponent steps) or WS'K (If opponent's range move is a TC) & counter hits opponent's slower range attack that was meant to counter Sig's set up 4B+K'A+B.
sig can also try SSH'K for this mix up. If the opponent is clever she/he will try TCs like Asta's 66K.
K is good against shaky opponents who got 6K stunned. Like for: 6K counter hits, K stun hits, then 1K, or b6 if opponent G2.