Pencillin is generally recommended, as resistance in group A streptococcus is unheard of, and risk of rash with amoxicillin if actually Epstein-Barr.  For group A streptococcus a 10 day course has better microbiological clearance but probably no benefit clinically to 5 days.

For scarlet fever, treat for 10 days with any antibiotic except azithromycin (5 days).

Comparative efficacy of antibiotics vs gp A strep pharyngitis – Seventeen trials (5352 participants) were included; mixed adults and kids?

• no difference in symptom resolution between cephalosporins and penicillin (intention-to-treat (ITT) analysis; N = 5; n = 2018; odds ratio for absence of resolution of symptoms (OR) 0.79, 95% confidence interval (CI) 0.55 to 1.12).
• Clinical relapse was lower with cephalosporins (N = 4; n = 1386; OR 0.55, 95% CI 0.31 to 0.99; overall number needed to treat to benefit (NNTB) 50), but found only in adults (OR 0.42, 95% CI 0.20 to 0.88; NNTB 33).
• There were no differences between macrolides and penicillin. Children experienced more adverse events with macrolides (N = 1, n = 489; OR 2.33; 95% CI 1.06 to 5.15).

Evidence is insufficient to show clinically meaningful differences between antibiotics for GABHS tonsillopharyngitis. Based on these results and considering the low cost and absence of resistance, penicillin can still be recommended as first choice.  But not much logic in replacing any other antibiotic with penicillin! [Cochrane Database of Systematic Reviews. 4:CD004406, 2013. UI: 23633318]

Short courses (3-6 days) of amox, co-amox, cefuroxime/cefixime (cefalexin not studied), macrolides etc are actually better than standard 10 day course of penicillin, but more expensive.  [ Cochrane Database of Systematic Reviews 2012, Issue 8. Art. No.: CD004872.]

SAPG 2022 recommends penicillin but if shortage amoxicillin then flucloxacillin. For penicillin allergy, clarithromycin preferred, then erythromycin, then azithromycin. Third line cefalexin, then co-amoxiclav, then co-trimoxazole.