It really depends.
If you are looking for the highest APY you should check on tokengoodies.com or tron-radar.de.
Otherwise check which one of the SR makes the most for the Community.
I personally would vote for Turu if it was for longterm.
Not because I am part of Turu, but because turu is a team of well known tron OGs, most since 2017/18 active in tron.
Despite that the Community is amazing and Turu does really a good job in building great things on tron.
Also voting for Turu gives you elss rewards because they are not in top 27 and therefore SRC (c stands for candidate) but you get Turu airdroped if you vote longterm which makes it the best paying SR if you were to sell the received turu on justmoney.exchange DEX.
If you want to know more Check my video on YouTube.
Two parts about Turu in general.
Part1
Part2
Let me know if you have further questions about turu or tron in general 