In which case you would be officially insane, especialy regarding Blake. Blake has never played tennis that would even come close to beating Federer at his best. If he has
name me a single match or tournament he has played his whole career vs anyone that would beat Federer at his best, I look forward to any answer you could conjure to that one. Their matches vs each other alone would prove that, he wasnt close to winning in any of them except for his one actual win where he won in 2 close sets over Federer producing 58 unforced errors in 2 sets, so obviously would have won just playing a bit less awful that day. So you are forced to suggest Blake has never played his best tennis in any of his many matches with Federer.
Safin is a rather weak case too given his 2-11 head to head with Federer, but atleast he did have one day he beat Federer playing very well in an epic, and in a major encounter.
Again, as previously mentioned (try and pay attention); players playing at their best is completely, or at least rather largely, a hypothetical. So no, there is no match or tournament that i would cite. However, taking the elements of the players that I've seen when they are playing very well and then extrapulating those attributes - yes, i can see how Blake playing at his best would beat Federer playing at his best. 'Peak' Blake is faster, especially the first step, Blake is more athletic, Blake has more top end power and penetration. i also feel peak Blake has a better more damaging return than Federer at his best.
Now in the every day in and day out, of course Federer is superior!
LOL this one is rich and I happen to like Venus. What is Venus's best exactly.
1999- lost Australian Open quarters to Davenport 6-4, 6-0, lost French Open 4th round to Schwarz, lost Wimbledon quarters to 30 year old Graf in final tournament, lost U.S Open semis to Hingis, lost WTA final semis to Hingis.
2000- struggled throughout year with aging way past her prime Sanchez Vicario including losing to her in French Open quarters, had smackdown losses to Coetzer and Dokic, was 2 points from defeat to Hingis in U.S Open semis, and didnt win a tournament all year outside of grass or decoturf hard.
2001- lost 6-1, 6-1 to Hingis in Australian Open semis, lost 1st round of French to Barbara Schett. During dominant 3 month summer swing lost to Shaughnessy.
2002 and 2003- lost 5 slam finals in a row to Serena, lost to Zvonareva and nearly retired Seles in other 2 slam apperances.
So Venus playing at her best would beat Henin at her best on clay, or Serena at her best on rebound ace, or Navratilova or Graf at their best on grass. Yeah right.
Again, a players best is a hypothetical! But, why in the world would you cite some of Venus' worst matches in this discussion 
???
That makes absolutely no sense, and you should be smacked for doing so!
Peak Venus is faster, more athletic, and more explosive than any other woman who has stepped on the tennis court!!!
Some women at their peak can match her power off the ground; such as Davenport, Serena, maybe Pierce or Sharapova - or consistently on serve: only Serena. But none of those women are either as fast as Venus (Serena is a step slower) or have her reach. And no woman I've seen has her improvizationally skills.
Also I'm mainly talking about on a nuetral surface, namely a medium to fast hardcourt..
I take it you have never seen a Blake-Federer match. Federer has more winners than Blake in all of their encounters. Their best match was at the 2006 U.S Open which was definitely Blake playing at his absolute best, and still nearly losing in 3 straight sets. They ended the match with roughly the same unforced errors while Federer produced about 20 more winners.
