Having just gotten off the Fantasy and having sailed on RCI and other lines, I can tell you, you will have a lot of fun on the Oasis. They have great kids programs and the kids pool areas are actually bigger and more diverse on the Oasis (the ship is twice as big so that one is a given). The Dreamworks characters are there and frankly, the kids enjoy them just as much (provided they like the movies they star in).
In other words the potential to have a wonderful cruise is there on both lines.
However...
There is a certain "something" I found on the Fantasy. I don't want to use the word "magic" but whatever it is, it makes a difference. As many others have posted and argued on these boards, there is a certain something that makes people feel that the extra money you usually spend on DCL is worth it and I have to say I felt it too. Having finally taken the plunge, I have to say its "real".
But, what many people don't realize or understand (or want to understand) is that just because you are acknowledging you can have fun on other lines for less money, you are putting down DCL or implying they are not better (or, heaven forbid, that other lines are better
) I'm not talking about anyone in particular folks but you all know the kind of discussion I'm talking about.
The fact is that DCL is in fact more expensive. Like you just found out it can be a lot more expensive. For some of us, sometimes we have to pick between looking at other lines (which are very good as well) or having to wait to get the money needed for DCL (I booked two years in advance to slowly pay for it). Sometimes, we don't want to wait so much for a vacation. So sometimes we go for the less expensive option and have fun there too.
When I travel on another cruise line, I know its not gonna have that Disney "something" but the fact is I'm not expecting it to because I know its not Disney. I rate it for what it is and in the case of the Oasis, its a very fun cruise where you can have a great time. It's supposed to be different.
So all this writing just to tell you to take both. LOL Save the 2 grand and shop till you drop on your cruise, then take your time planning your DCL cruise and take it down the line. Variety is the spice of life! I assure you both will be a lot of fun.