I actually got into the pokémon series via the first PMD game. I really enjoyed it and then moved on to the main series game. Bought the first PMD about 3 times due to losing copies and for it's multiple versions.
The second one I have not played as much, but I really admire the story for being darker without being overly irksome like in B/W. And of course there's the 2nd and 3rd ranger games (the first one had some poorly thought out mechanics) and pokémon Link/Trozei. I even strangley like Pokémon Dash.