I wanna keep this thread on the front page because I think it's an interesting discussion now that we have another Slam winner in this group.
Here's how I'd rank them from best to worst.
Delpo's got a really impressive Slam win which featured back to back victories over Nadal and Federer, and he's also had other great Slam runs which involved some seriously competitive matches against very good versions of the Big 3 (RG 2009, Wimbledon 2013, Wimbledon 2018, among others). Statistically, he lags behind several of the others due to his relative lack of big titles or even finals, but I think he was a better player than any of the others if not greater overall. I'm not the kind of guy who thinks he'd be a 4-5 Slam winner or something without injuries, but I think he'd probably rack up a few more Masters titles and the like like Medvedev and co. have done. Possibly even a YEC in him, he's had a few decent performances there such as in 2009.
Medvedev is probably the most consistent player of this group. Even you have doubts about the, ah, relative strength of his wins, and I do, his consistency across the hard court events is pretty impressive all by itself and I think it merits him a mention here. The problem is that I don't rate his peak level all that highly because his game is too technically limited, but he is a great tactician and one of the best defenders out there given his height disadvantage so he has a very high floor if not a high ceiling. He's also not nearly as good on grass and clay courts, but his success on hard courts almost makes me forgive that failing.
Thiem has brought a fairly high level of play on hard and clay courts, and while his US Open win was quite the meme run, he's got a few nice finals such as the AO 2020 run and his back to back WTF finals which included some nice wins over the Big 3. In fact, if I were to pick any player under 30 to beat one of the Big 3 in a match, my safest bet would be a prime Thiem imo. His problem is a deeply concerning mental weakness which, imo, cost him the AO and WTF titles and very nearly cost him his sole Slam win. It's why he only has a relatively disappointing two big titles to his name rather than four or five as I'd expect from a player of his caliber. Still a good player but he really should be better.
Cilic pretty much has one really good tournament, and that was an absolutely shocking performance. It was probably the best single tournament anyone in this list has played, but the problem is that his stats outside of that tournament, while still perfectly respectable (two Slam finals and a Masters win), don't really stick out from the others, so I rated Thiem, Medvedev, and Delpo higher due to their more balanced resumes and the fact that they could bring a reasonably high level to multiple matches. But we still can't ignore that US Open run so he places in at a firm fourth.
Zverev has a high ceiling as some of his more impressive performances like Rome 2017, WTF 2018, and a few of his this year might indicate, but he doesn't bring this level as often as he should. I mean, how many meme matches does this guy have? Still, he has a nice repertoire of achievements which includes the WTF win, an Olympic Gold Medal, and several Masters. Zverev needs to more consistently bring that kind of level to the Slams, but I will concede that he has made some definite improvements in that regard over the last two years.
Tsitsipas is great on clay but he has so many holes in his game, especially the return, that he gets considerably easier to pick apart on other surfaces. Still, he has a Slam final which he reached playing in mostly good form, a WTF win, and a Masters. Dude just plain sucks on grass though. Might be even worse than Medvedev on clay which is saying something.
Dimitrov has three Slam runs that merit a mention when discussing his career: AO 2014, W 2014, and AO 2017. All respectable runs where he brought the fight to an actually good Big 3. In fact, I'd rather point to those results first rather than discuss his actual WTF and Masters titles. I mean, let's be honest, he kinda vultured them. I'd take his career over any of the other lost gen crew save for Thiem, but I won't deny that it's a bit disappointing as a whole when you look at the hype he had.
It's a bit of a travesty that Nishikori never managed to win at least a Masters considering how many deep runs he's had, both at Slam level (where he boasts a very respectable 12 QF's) and outside the Slams. Like Medvedev, Nishikori is (or, well, used to be) a very consistent player who could reliably make it somewhat far in any given tournament he entered. Unfortunately, his ceiling was never that high, which showed in the many matches where he just rolled over for the Big 3 after reaching those QFs or SFs. There is an exception, however, and that is the 2014 US Open, his main claim to fame. I just don't think it's strong enough for me to rate him any higher than this, however.
Raonic? Not sure what to say, tbh. You could feasibly swap him and Nishikori (or even Dimitrov but I think that'd be a slight stretch), but I put Raonic here on pretty much nothing else other than that I rate Nishikori's Slam final higher. There's not a lot in it.
Let's add Berrettini here. I think he's set to pass Raonic and Nishikori by the end of his career because he has the right weapons to be somewhat threatening on all three surfaces. He could make some more good runs, possibly vulture a Wimbledon given the field. Right now, though, I don't think his one Wimbledon final is enough to lift him out of the second-worst spot. Not to mention, his game has more holes than Swiss cheese.
I don't think Rublev is that good. He wins the tournaments he's supposed to win (your 250s and your 500s), reaches a few Masters finals and Slam QFs, and loses to who he's supposed to lose to. The thing is that he's very good at winning "Mickey Mouse" tournaments and thus inflates his ranking.
