Hi Trevor,
Cuiv has reviewed a few different filters over the last year.
I have watched some of his reviews and to my memory the Askar D1/D2 seem to give the best results. I think there is also the C1/C2 set for a lower price than the D1/D2 filters.
I hope this helps...
Cheers,
V.
SVBony SV227 5nm SHO Filter Set
https://www.youtube.com/watch?v=BwMT_7FgVS0
5nm HaOIII filter is CHEAPER than the Antlia ALP-T
("Hang Technology", who is an unknown in the filter world.)
https://www.youtube.com/watch?v=7alOZ13i7TQ
SVBONY SV220, basically an L-eXtreme for half the price
https://www.youtube.com/watch?v=uDtIbU2j3uM
Askar Colour Magic D1 and D2
https://www.youtube.com/watch?v=e1EnBrXBOUg