Uncle Ben's Long-Grain Converted Rice is my rice of choice. It's virtually foolproof & absorbs that wonderful saffron flavor & color beautifully.
Oh, & I also agree with ChefJune - don't know where you got the idea that there's tomato sauce in Paella. Fresh, cooked diced, even stewed I've seen - but never ever tomato sauce. The rice gets its golden color & distinctive flavor from saffron initially, & then the juices trickling down from the meats, veggies, & seafood as they bake.
There are many variations & different types of Paella - some with just seafood, some with just meats/game, some with both - but I've never come across one that used any type of sauce, tomato or otherwise.