If you don't have a powerhouse Gauntlet crew for SEC, Gangster Spock is an excellent choice. 8472 has only slightly lower proficiency than Spock, but obviously Spock will also be bonus crew in a lot more events — thus, my advice is Spocko. But if you go with 8472, it's not a terrible choice, either. May come down to which one you personally like the most.
Could you please continue the petty bickering? I find it most intriguing. ~ Data, ST:TNG "Haven"
The Invader wouldn’t be bad - it might even have the edge on voyage score when FF despite having only two skills - but Spock is a top-tier gauntleteer and an iconic version of the character. Event usefulness may be tempered by his poor base skills at 1/5*...but he would be more useful than the Invader in any case.
Either would be good in a SEC-featured gauntlet - Gangster gets trait buffed about 50% more often than 8472 in gauntlet and has a third skill and I have even used him on a couple of voyages. 8472 has been a solid 2nd-string shuttle and voyage for me, as one of the earliest 5's I FF'd.
Comments
Could you please continue the petty bickering? I find it most intriguing.
~ Data, ST:TNG "Haven"
More importantly, however: