>>24853355They're both good. They have flaws but I can't think of a single Pokémon game that doesn't, and I think Gen 5 is the second best gen, after Gen 4.
Play BW1 first, obviously, and if you're emulating or have an action replay unlock hard mode in BW2 to play it with that the first time, since you can't get it until postgame unless you have a friend with Black 2.