Devotion is devotion.  It  makes no difference if done in a group or alone.  If your mind is involved in remembrance of Krishn, it makes no difference if you are doing alone or if you are with other devotees, because devotion is very personal. In our scriptures, meditation is described  as done in isolation. 

Whatever way of devotion is convenient and possible for you is fine.  However, when there are devotees doing meditation together, they all have their own vibration of devotion in the atmosphere and sometime this can help to uplift another devotee.  So both  ways are equally good, either doing alone or doing in group.