I use small caps in my document for all abbrevations, even though it can be challenging sometimes (e.g. in abbreviations like "dACL"). I also use old-style figures in the body of my text but I believe that one shoule use lining & fixed-width numbers in tables and lining proportional numbers in math.

The question now becomes, do I keep the small-caps in the table (see MWE below) and use lining figures or small caps and old-style figures? Or do i use all caps in the table to match better with the lining figures?

Any input is greatly appreciated.

\documentclass{article}
\usepackage{libertine}
\usepackage[libertine]{newtxmath}
\useosf
\usepackage{booktabs}
\newcommand*{\abbr}[1]{%
   % Format abbreviations as small capitals
   \textsc{\MakeLowercase{#1}}%
}

\begin{document}
\begin{table}[hbp]
    \centering
    \begin{tabular}{llll}
    \toprule
               & \abbr{SNS}-3615  & \abbr{SNS}-3655  & \abbr{SNS}-3695  \\
    \midrule
    \abbr{CPU} & Intel Xeon 4110  & Intel Xeon 4116  & Intel Xeon 4116  \\
    cores      & 8                & 12               & 16               \\
    geheugen   & 32\,\abbr{GB}    & 96\,\abbr{GB}    & 256\,\abbr{GB}    \\
    power supplies & $1\times 770$\,\abbr{W} & $2\times 770$\,\abbr{W} & $2\times 770$\,\abbr{W} \\[2ex]
    endpoints (standalone) & 10000 & 25000 & 50000 \\
    endpoints (\abbr{PSN}) & 10000 & 50000 & 100000 \\
    \bottomrule
    \end{tabular}
    \caption{Specificaties van de Cisco secure network servers (\abbr{SNS}) waarop Cisco \abbr{ISE} draait}
    \label{tab:ise-sizes}
\end{table}
\end{document}

I use small caps in my document for all abbreviations, even though it can be challenging sometimes (e.g. in abbreviations like "dACL"). I also use old-style figures in the body of my text but I believe that one should use lining & fixed-width numbers in tables and lining proportional numbers in math.

The question now becomes, do I keep the small-caps in the table (see MWE below) and use lining figures or small caps and old-style figures? Or do I use all caps in the table to match better with the lining figures?

Any input is greatly appreciated.

\documentclass{article}
\usepackage{libertine}
\usepackage[libertine]{newtxmath}
\useosf
\usepackage{booktabs}
\newcommand*{\abbr}[1]{%
   % Format abbreviations as small capitals
   \textsc{\MakeLowercase{#1}}%
}

\begin{document}
\begin{table}[hbp]
    \centering
    \begin{tabular}{llll}
    \toprule
               & \abbr{SNS}-3615  & \abbr{SNS}-3655  & \abbr{SNS}-3695  \\
    \midrule
    \abbr{CPU} & Intel Xeon 4110  & Intel Xeon 4116  & Intel Xeon 4116  \\
    cores      & 8                & 12               & 16               \\
    geheugen   & 32\,\abbr{GB}    & 96\,\abbr{GB}    & 256\,\abbr{GB}    \\
    power supplies & $1\times 770$\,\abbr{W} & $2\times 770$\,\abbr{W} & $2\times 770$\,\abbr{W} \\[2ex]
    endpoints (standalone) & 10000 & 25000 & 50000 \\
    endpoints (\abbr{PSN}) & 10000 & 50000 & 100000 \\
    \bottomrule
    \end{tabular}
    \caption{Specificaties van de Cisco secure network servers (\abbr{SNS}) waarop Cisco \abbr{ISE} draait}
    \label{tab:ise-sizes}
\end{table}
\end{document}