There are very many Linux distributions available, and the major ones have variants as well.
For just the example of Ubuntu there’s lubunto, kubuntu, xubuntu, ubuntu-mate, ubuntu-budgie, and Ubuntu -studio just to name a few. Ubuntu itself can be considered as a Debian base plus extras. Then there are many distributions derived from Ubuntu ( Mint is one I used to recommend to new Linux users with relatively new hardware).
There are several distinct bases other than Debian, often categorized by their package management system. RPM, Slackware, Gentoo, Android are examples of distributions that each have different package management that have their own families of distributions.
A recommendation really does depend on what uses one has in mind, what specialized peripherals might be involved, how much one desires “slick” graphics effects, performance needs, and whether one is needing consistency of the user interface among several machines which might range widely in hardware beefiness, just to name a few factors.
And then there’s the experience level on computers, programming experience ( or desire to learn ), are there multiple users ( and whether including children), desire to share resources on a network, that can come into play.
Often it’s best to find the distribution that the computer manufacturer has already provided drivers compatible with, but this isn’t as much of a factor as it once was. Still it’s a good idea to Google something like “[brand] [model] [distribution] problem” before trying. (Example search: “Lenovo Yoga 11e Ubuntu problem”)
https://distrowatch.com/ has a good overview that includes popularity rankings
If pressed to make a recommendation with no further information I’d second the recommendation to start with an Ubuntu. Mostly because it’s pretty well supported and common and makes reasonable assumptions about the “average” user.