Depends on what you want.
You can't want to be someone wanting world firsts while at the same time being able to bail when the mood hits you. If you want to be competitive, join a competitive guild. If you want relaxed, but capable raiding, join a relaxed guild that raids 2 - 3 nights a week.
Those type of guilds won't hate on you for missing a night to spend with the kids or the honey, or guilt trip you if you leave early cause of family.
Example, back during Vanilla during a Nefarion attempt our paladin suddenly bursts on vent "gtg, baby's coming" and he and his wife's mage disconnect. Rest of the night was not filled with us hating on them for daring to leave for something as trivial labour :P. We spent the night inbetween attempts wondering if it was a boy or a girl and if he/she would resemble the mother/father.
Get with a guild that suits your tastes, anything is better than the hit or miss frustration that is LFR.