Depends on opponents. Some are stronger receiving overhead and some are stronger at receiving low serves. Also depends on your own abilities at taking the third shot. Are you comfortable in taking the shuttle from the invents overhead or do you prefer it if they hit up from your low serve.
If they have a weak backhand I generally drive serve it to their backhand , then it generally goes up where I can kill it. Short serves against people thAt can fight against drive serves and smash down with high serves.
Singles players ..please share your thoughts about the topic
Its singles - the serve has very little importance compared to doubles. With that in mind, try all the different serves:
Low serve: doesn't let opponents attack downwards overhead, but does give them deceptive net opportunities which are dangerous. Only use if your opponents net skills are less threatening than their overhead skills. It is a risky serve if you cannot defend your deep back corners properly e.g. you worry about drives or pushes to the backhand
Flick serve: good to force your opponent back in poor balance, but risky against a fast opponent with a good half smash. Use this to make your low serve safer.
High serve: good against players who either struggle with having lots of time (the like a fast game) or have a weak overhead attack. Only players who are accurate will cause you trouble with this serve, hence it is used a lot below competition level. It is very safe.
Drive serve: only use it down the middle as a means of trying to get the shuttle deep behind your opponent quickly. It can be risky as it gives you very little time to get to base, and can be attacked by a skilled opponent. However, at a lower level of play, it can work very nicely.
The key thing: mix up your serves. If you always serve short, your opponent will simply stand further forwards.
The advice I have just given applies to singles and to doubles. As a singles player, I would start with low serves, and then use flick and drive serves as well. However, if I were more worried about my movement, or I had a very good defence, I would use more high serves.