Why are you wanting to switch? Are you losing super slowly, having sides, FOMO?
I've had a lot of success with tirz that I've worked up to 15mg/week over the past year, but have dabbled with Reta and Cagri just to see if it could speed things up. So far, I've been unimpressed, but it seems to be highly variable from person to person.
Recently, I've decreased the amount of days between tirz shots, and I'm satisfied again. I'm coming off of my best month in like half a year, so I may just keep doing tirz solo for the time being.
I recommend considering the same tactic as long as tirz is working.