Both of my parents, in their 70s, had the Pfizer booster without any adverse effects. They have felt more comfortable in public settings knowing they have additional protection. The deaths of similar aged friends has made them cautious.
My wife, in her early 40s, had the Pfizer booster which made her tired for a day. She is more comfortable teaching in her classroom but remains extremely cautious as we have a son who needs to be protected from CoVID.
The CDC has recommended an additional dose of any vaccine for anyone who had the J & J vaccine and those who meet certain criteria who had Pfizer or Moderna.
COVID vaccine: CDC expands booster rollout, OKs mixing shots
If I was to take a booster I would opt for Pfizer. The Pfizer dosage is less than 1/3rd the strength of the Moderna vaccine. The study data showed that similar percentages of Pfizer and Moderna subjects reported adverse effects. Based on anecdotal reports it seems that the adverse effects are stronger with Moderna. I had Moderna with flu like symptoms for 24 to 36 hours after each dose in January and February.
I know that I could get booster but having had two doses of Moderna I likely have highly beneficial antibody response already and my public exposure is limited. Topping that the virus is on a decline in my state. If cases continue to decline and my exposure level remains low I may wait for the next generation of booster specific vaccines. If I had significant public exposure I would jump on the opportunity to get a booster.