Land based or Liveaboard.... Might depend on really whether you have previously experienced it from both perspectives.
I had done it, leading groups, quite a few times as liveaboard.
After that, land based seems to work better for me, at a 30-40%+ cheaper price, plus, you actually get to see a bit of these islands.
In that the OP has already selected the land based route, and he has selected SCUBA Iguana- the best dive op (IMNSHO), he will see the Galapagos as most North Americans would never even think about it- skipping a liveaboard? What is he thinking?
We North Americans have been so brainwashed by the dive magazines and marketers of liveaboards (they are one in the same), that we can't see the Galapagos the way Europeans do- as a land based opportunity.
Larger numbers of big animals up North to Wolf and Seymour... but can you really embrace that three day round trip on a small boat in high seas? People do it all the time, but they really don't tell that - the horrible part of an otherwise great story of dive travel.
I prefer a 10 day trip, see the islands, see the actual habitats in the highlands, crawl through lava caves, get in two or three dives on any given day, I'm good. You see the Mobula Rays, the Sharks, the Seals, likely all the same stuff that the people spending $$$ on a liveaboard see- but instead, you get to eat dinner at a different restaurant every night, walk through the Parks, enjoy nice airy rooms with dry beds that do not rock.
There are much cheaper locations and more certain ways to see Whale Sharks than making that even a minor focus of such a trip.
Liveaboard or Land Based? It is all a personal choice... if the entrenched marketers allow you to think you have that choice. Like the quote from Scuba Diving Magazine, "Galapagos Liveaboard- Our readers would have it no other way". Well, of course they wouldn't- your advertisers make sure of that. The magazines aren't going to let you know about land based because they simply don't have the money to advertise in our magazines.
Like I said, it is really a factor on whether you have experienced it both ways, having any basis for comparison.
There really isn't a great reason to return to the Galapagos more than once in a dive career. You come and see the four "face card" creatures, if you're lucky (and dive often) you'll see one eat another one. Other than that, you're done. If you haven't taken the time to see the stark natural beauty of the islands- you've missed what is literally the other 50% of the reason to travel here. I don't say that about many other destinations- but the Galpagos is an exception.