Honestly, I would recommend some D'Addario XL's in a medium gauge. See how you like those and you can get more recommendations. If you want something that's more mellow, more zingy, higher tension, lower tension, brighter/darker, thumpier, etc., you can get recommendations relative to those.
They're a good all-around string that are fairly neutral in the grand scheme of things. Once you know more about what you want you can be steered in that general direction by all us wonderful guys.
edit: They're also affordable and readily available at most guitar stores.
www.juststrings.com is a good source once you want to expand your horizons outside of what's available at Guitar Center/Sam Ash.