The bottom line for all of these websites is how do they stack up to the realities of serious genealogical research? Even though they all claim to have millions or billions of records, what does this actually mean? What do they have online and what is not yet (or may never be) online in these larger websites? Shouldn't we be looking at categories of records where ever they are found rather than focusing almost exclusively on particular database programs?
For this evaluation, I am going to select some record types from the list of categories on the FamilySearch.org Research Wiki. This particular resource lists different categories of records available in various political jurisdictions around the world. For example, here is a screenshot of the main article for the United States with an arrow showing the list of types of records that a genealogist may wish to consult in a thorough research effort. The list is too long to show entirely in the screenshot.
Of course, we could argue the utility of some of the types of records listed, but the question here is whether or not these records are available through any or all of the named large database programs. The way to tell this information involves some considerable examination of the contents of the databases. Because records are being continually added to the collections for each of these entities, any such evaluation involves a snapshot in time which could change today or tomorrow as records are added.
Of course, I can easily choose records that I know each of the large databases are missing to compare the websites. For example, I could choose records from Panama which were, until very recently, only available from FamilySearch.org. Now, however, due to the sharing of those records, the same collections on FamilySearch.org show up on Ancestry.com. The idea here is not to compare the websites with each other, but to discuss their collections from perspective of looking at them all at once.
One very obvious limitation in determining whether or not a particular database contains any particular type of record is that none of these larger companies list their records in the same way. FamilySearch.org, findmypast.com and Ancestry.com have compiled one long list of all of their records. FamilySearch.org does this through its "Browse all Records" selection. Ancestry.com has its "Card Catalog." MyHeritage.org has a hierarchal list of all of its collections but it is necessary to select a particular category to view all of the records available in that particular category. I am not here criticizing any of the methods of categorizing the records. They all work off of a filtering system and just use different filtering methods.
One reason for making this type of comparison is to determine whether or not a particular type of record you are searching for even exists in one or more of these programs. This is a good reason to visit a local FamilySearch Center, where all of these programs, are available for free access where you can work with each of the programs before subscribing. Mocavo.com is completely free but searching is limited to one database at a time. Their advanced search features are subject to a subscription and this feature is not available at FamilySearch Centers.
It is pretty easy to find things that none of the database programs have available. All I really need to do is go to collections that are not yet digitized or are available only in specialized online websites. For example, none of these large programs have all of the General Land Office records available from the United States Bureau of Land Management website. Likewise, there are millions of records waiting to be digitized in the U.S. National Archives.
Now, let me select some areas from the Research Wiki list to illustrate what is and what is not found in the large online database programs even if there are large online collections of the same types of the records.
I will start with Land and Property records. If I focus on one state, let's say Utah for example, they stack up as follows:
Ancestry.com 1 mining record
Mocavo.com Possibly, it is hard to tell from the long list of Utah collections.
One more example should be sufficient to illustrate my point that before we spend a huge amount of time searching in these large online database programs, perhaps we should determine if they even have the types of records were are searching for. Here is another example with Water Records in Utah:
Mocavo.com Very possibly, given the variety of publications
Since these examples show that certain types of records are not commonly included in the large database programs, we should all be aware of this fact and be careful to extend out searches to more particular types of records and where possible to records that may not yet be digitized.