First and foremost, you need to get the help of a reputable cruise specialist. Their services are free to use and they have a wealth of information that will help you narrow down the multitude of options available. They can definitely make it much easier on you and save you alot of hassle.
Now, with that said, every cruise line out there has their fans and their critics, so you'll get as many different viewpoints as there are people. Keep in mind that like I always say, 'what one person loves, another will hate', so just because someone thinks a particular cruise line is wonderful, it may not be suitable you you.
But it sounds like you've got a good start and now just need to narrow down where you want to go.
We've been on 47 cruises on 11 different cruise lines in many parts of the world and the one thing we learned a long time ago; once you've gone on a cruise, you're going to be hooked and will want to go again and again. And that's the fun part about cruising is trying them all until you find the best one for you based on your needs, budget, and lifestyle.