The best top line up that we have had in the last few season is (Note: Based on the most used line up for the season in terms of minutes):
Smart
Brown
Tatum
Horford
RWilliams
In 2021/22, this top line up (the most used line up) was on the court for 34 games, put up a staggering +218. A net rating of 24.6, look at whatever stat you want, this was the best line up.
The line up of:
Smart
White
Brown
Tatum
Horford
in 2022/23 was the top line up and used in 35 games for a +103, NRTG of 12.2. Not bad, but not nearly as good as the 2021/22 2-big line up. I think the only reason they didn't go back to Horford and Williams in 2022/23 was because Williams was injured so much, particularly at the start of the season. Williams was never the player in 2022/23 that he was in 2021/22.
For this season, we have Holiday and Porzingis instead of Smart and RWilliams. So which way do you go? More like 2021/22 or more like 2022/23? We can easily do either, at least to start the season as everyone is healthy.
I only real argument in my mind against starting Horford and Porzingis is that our depth does not support this as well as starting White and bringing Horford off the bench (and I am assuming that Holiday starts in any case). I am less concerned about who starts than what line up is the most used (although generally it is best if this is the same).
I say go big or go home, the Horford/Porzingis should be the primary, most used, starting, finishing line up.