This is tricky, since you're based in KRK, if you're in WAW or can re-position to WAW easily I might have recommended TK. Even so, you need to plan your trips to US carefully so at least 3 trips with TK within 12 months along with intra-Europe trips in between with LO (these earn 100% of miles). If the above scenario gives you nearly 40000 miles within 12 months, perhaps take TK Comfort Class to help boost your miles and status.