Read everything you can from FR (Frank Retes) here and elsewhere, use the archives too. Then read the monitor husbandry information at proexotics.com. Then read it all again. Honestly after months and months and months of reading what FR and others say everyday I STILL go back into the archives and read it all again and again. I'm dumb like that, I need things beaten in to take hold. Consider it's all really simple, that's the sad part haha.
You will know what monitor best fits your needs once you have a good basic understanding of what it will take to properly care for one. It's your choice alone, honestly no one else knows your situation well enough to recommend anything. Who knows, you may end up not wanting one or really wanting a rarer species not generally worked with. The moral of the story? Do your homework and you wont have to ask.
Good luck -
Tom