I have owned every format of TOS from some very low quality VHS tapes in the 80s to the DVD, HD, and blu-rays.
I can take or leave the new FX. Overall I believe the new FX are better than the old. Sometimes the obviously CGI ship fly-bys look cartoonsish but they're better than nothing. And TOS was written and directed knowing it had limited costly special effects so you can understand the story with bad (in today's standards) and sometime totally absent special effects shot.
I'm old school so I personally would pick the original shots if allowed only one but since I have the blurays and can look at the old effects whenever I want I always watch the episodes with the new effects.
The best thing about the remastering IMO was getting rid of the spots and film blemishes. That makes getting any remastered version worthwhile