Welcome to Cruise-Chat hjello! Have you spoken with a T/A about cruiseline choices, age requirements and other issues that will be important factors in choosing your cruise? That would be the first step in my opinion. HAL has a restriction of 12 months of age on transAtlantic and some other itins. Alaska and the carib age minimum is 6 months for them.
Have you ever cruised before and if so on HAL? There are some differences between the lines in terms of average age and the choices for entertainment and other things geared toward the target market of the lines. You'll find this site very useful in gathering info for cruising but, again in my opinion, you should not replace the guidance of a cruise professional. If you've sailed regularly you may not need such direction or information but if you're new to cruising get info here AND from someone who books and deals with the various cruiselines daily for good advice.