Both Kedarkantha and Brahmatal are equally beautiful trek. Brahmatal Trek can be best enjoyed during winters though whereas Kedarkantha is an all-season trek.
Kedarkantha or Brahmatal would be best for beginners. last year in feb 2019 there was high alert in Uttarakhand so we did climbing of three days in one day and did the Brahmatal summit. So it was little difficult because we did it in one day but if the climate is good you would have 3 days approx so it would be much easier.
The Kedarkantha trek is definitely the best choice for a group like this. The Brahmatal trek has some tough patches, and in a group of 10, there are always 1 or 2 members who are unable to handle challenging stretches like this, and the experience can be ruined for them. The Dayara Bugyal trek is a good option too, but with Kedarkantha, the thrill of summiting a peak and doing one of best winter treks is something you can’t get on the other treks. In the first week of march, you can expect snow and cold weather, so do carry the right gear.