Well, it depends upon how you view the character and what you think an Indy story should be like.
The Marvels are looser in many ways. They tend to involve a lot more MacGuffin quests of the authors' invention, while the Dark Horse ones were more inclined toward basing Indy adventures around existing myths and legends. The Dark Horse ones are more... thoughtfully planned; Dark Horse's were all miniseries, each with a defined story arc, and gave the impression of having been done when somebody had had a specific story idea they wanted to do and that prompted DH to do a(nother) Indy series, whereas Marvel had a regular, ongoing monthly series, and tended to have stories that were more 'whipped up'
as needed. Dark Horse also benefited from some years of advancing reader expectations of what a licensed comic series could and should be, and the DH comics seem to have had more care put into them with regard to fitting them into a detailed Indy timeline and canon, but in Marvel's defense there was hardly anything for them to worry about when theirs started - just the first two movies, really.
If you order $100 or more worth of stuff from the online Indy store
, they'll add in a free vintage Marvel Indy comic, which may help give you a taste of what the Marvels were like if you don't have any, without you having to make any special investment of time or money to get them. They don't distinguish between comics, though - they just give you a randomly selected comic (it could even be from one of the movie adaptations, or any one of the 34 issues of the regular series), so it's hardly the ideal way to go about trying to plug a hole in one's collection if one already has most of them.