I like Andy Murray, and if he had been born 10 years earlier or later he would have won 10+ grand slams. He has landed slap bang in the middle of literally the 3 GOATs (alongside Rod Laver) of his sport and still competed. The only other person on this list in the conversation is Ronnie.
I disagree - if he was born 10 years earlier, and was competing with Sampras/Agassi/Becker in the 90s, and Sampras and early Federrer in the early to mid 00s, I can't see him winning more major titles than the 3 he has; if he was born a decade later, and still coming up against an ageing Nadal/Djoko, he'd still be losing to them right now anyway, but maybe over the next, say, 5-6 years he might win some more (especially as it looks like the weakest ever era of tennis players, but that could just be because Nole and Nadal are still playing). Sampras and Agassi are way, way underrated - Agassi especially, still a top 5 returner of all time for my money.
But then again, I'd also not have Hamilton (I'd argue his cars are even more dominant than Schumachers were in most of his world titles, and even then he lost 2/3 of them whilst being in that dominant car), Ennis Hill OR Holmes (Farah would be closer but still not quite there for me); of the 6 I voted for Kenny, up there with her hubbie and/or Hoy as the greatest ever British Olympian (with Regrave and probably Ainslie rounding out a top 5 of Olympians).
And I am probably being harsh there on Adam Peaty - in terms of pure statistics (world Records, margins of victory, etc) across two Olympics he was ridiculously dominant and nobody can touch him on that front - even Phelps at his most dominant was not regularly beating the entire field by as much, or holding 20 of the top 20 fastest times of all time (as Peaty did in April 21 in the 100m breast stroke) - since then, Kamminga has gone 57.8 which would have been good for 13th/14th - but then Peaty went quicker 3 times at the same meet, so thats now 19 of the top 20 (with Kamminga having the 16th/17th spot) and 7/8 of the next 10.
Cavendish (and maybe Wiggins/Froome) would also be up for consideration - people forget just how good Cav was (still holds the record for most sprint victories at the TDF, and 2nd only behind the GOAT Merckx for overall wins) at his peak.