What is the best alternative to Microsoft Excel on iPhone?

Microsoft Power BI, S tier, #1 in data analysis.

Is there a free alternative to Microsoft Excel?

Yes: Microsoft Power BI (S tier, #1) is free, with no in-app purchases.

Yes. 2 apps rank above it in data analysis: Microsoft Power BI (#1), Tableau Mobile (#2).

Microsoft Excel is A tier, #3 of the 6 tiered apps in data analysis. Here is everything that competes with it on iPhone, in tier order.

1
Microsoft Power BIShigher tier
Free download · ★ 4.7 · 396,013 ratings · score 98
Mobile app for viewing, annotating, sharing and getting real-time data alerts from Power BI business analytics.
2
Tableau MobileShigher tier
Free download · ★ 4.6 · 5,693 ratings · score 91
Mobile app for viewing and interacting with Tableau dashboards from a Tableau Server or Tableau Cloud account.
4
Google AnalyticsA
Free download · ★ 4.7 · 31,855 ratings · score 82
Free Business app for monitoring website and app performance and key metrics from a phone.
5
Vernier Graphical AnalysisB
Free download · ★ 2.4 · 729 ratings · score 71
Collects, graphs, and analyzes data from Vernier sensors, with manual entry also available for science students.
6
DataAnalysisLiteD
Free download · ★ 3.9 · 9 ratings · score 53
Plots and fits x, y data on iPhone, with curve fitting, standard curve prediction, and kinetic data analysis.

What is the best alternative to Microsoft Excel on iPhone?: Microsoft Power BI, S tier, #1 in data analysis.
Is there a free alternative to Microsoft Excel?: Yes: Microsoft Power BI (S tier, #1) is free, with no in-app purchases.
Does anything rank above Microsoft Excel?: Yes. 2 apps rank above it in data analysis: Microsoft Power BI (#1), Tableau Mobile (#2).