Pearson Vanguard! Those have made countless ocean crossings, not super roomy but if you don't want to have any hull issues those are cheap and reliable. You can get fully cruising for under 15k including the price of the boat. Steer clear of production boats such as Catalina, Hunter, Irwin, Columbia, etc. if you are planning on doing some blue-water.
But with the budget you are talking about you can step up to lets say a CSY, Young Sun, Cape Dory, Valiant. All of those I really like.