Edited 5/18 to add more notes to each.
Falken RT660 - my favorite do all tire. They're damn fast for the first 10ish min of a session before greasing up a bit. Even then they're manageable. Did 7 days on track (6 at VIR and 1 at Summit Point on the Jefferson circuit), plus about 8k miles and sold them with 4 to 6/32 on all of them. (But worn shoulders). Could have used for another full weekend easily, but I already bought new tires partway through the season so decided to throw new tires on for 2023.
Additional notes: I've burned through 1 set on my GTI, and IIRC 2 or 3 sets on my old Mazda2 on track. These things are basically the best qualities of the old RE71R and just as sticky, but have considerably stronger shoulders that resist wear a bit better than the old Bridgestones did. I have NOT driven the new RE71RS. Just to be clear I cannot compare to that one. These are not amazeballs in the rain, but they're not dangerous or anything either. At full tread they're pretty decent but will hydroplane in deep standing water. Not as good as Conti ECS for STANDING water, but better if the track is just damp. I would get 4-5 days on an abrasive track (NCCAR) on my Mazda2 for reference. I wouldn't be at the cords, but low enough (say 2-3/32) that I'd sell them off or give them away at that point.. I joke that it costs me more to run at VIR for $550/weekend than it costs to run at NCCAR for free. These things do heat cycle out eventually. Wasn't super noticeable until my last weekend on track with the GTI. Probably had about 20 hard heat cycles over the first 5 days on track. They were noticeably less grippy my last time out on them in December for days 6+7 on track. Also these things get pretty loud as they wear more.
Kumho V730 - believe is a bit slower than RT660 but may last longer (only one track weekend and a couple auto-x so far). Fucking terrifying in the rain with standing water. Fine in the damp.
Additional notes: I'm partway through my first "set" of 6 tires now. I have (4) 245/40R17s and (2) 255/40R17s. I have tire machines so plan is to swap between the 245 square setup for track (so I can rotate front/back/left/right throughout the weekend as necessary), and run a reverse staggered 255/245 setup for auto-x. They have decent feel overall. More responsive at full tread vs RT660 at full tread, but feels similar to a worn RT660 as the Falken will have more tread squirm when new. These don't feel like they have as much "bite" as the RT660 did on turn in. These things are great for the price *IF* you don't plan to run in the rain/have another set for rain. A set cost ~$200 less than RT660 which was why I went with them this time around. In this video you can see how close I came to losing my shit. Audio scrubbed for obvious reasons.
This was plain and simple me not driving within mine/the tire's limits. There's a big "river" that runs across the back straight in hard rain. This happened in the second session of the day and it had gotten way worse vs the first session.
Hankook RS4 - lasts forever. Vague feel.
Additional notes: LOTS of meat on the shoulders. Lasts a long time. On my Mazda2 I averaged 7-9 days on an abrasive track (NCCAR prior to the "kink" being added). They feel pretty good if you stretch the shit out of them. I ran a 225/45R15 on 15x9 wheels, and 195/50R15s on 7.5 or 8in wheels. Never get greasy unless you're overdriving the balls off of them. Worse in the rain than RT660, way better than V730 though. Not great even in the damp but not what I'd call unsafe. Just much lower limits even when full tread.
Original RE71R - This tire is no longer available and is
NOT to be confused with the newer RE71R
S - just mentioning as a basis for comparison for those who HAVE used it before - fast for a lap then falls off. Wears like soft cheese. Not available anymore but figured I'd mention for reference. Haven't used the new RE71RS yet.
Additional notes: FAST for a single lap or two. I went through 3 sets of these on my Mazda2... I averaged 2 days at NCCAR for comparison. About 25% the life of RS4s. IMO they're better for auto-x than any of the other tires I tried, except MAYBE the RT660s. These things were awesome in the damp and pretty decent at full tread in standing water (but still not as good as Conti ECS). Super responsive turn in. Very "edgy" to drive. Once you exceed the limits you know it and it communicates well. Likes a very "precise" driving style. Edges wear out super quickly.
RT615K+ - Slow vs the above, but actually a lot of fun because they like tons of slip angle.
Additional notes: Never ran on my own cars, but I've driven a few friends' cars on track. These things are FUN to drive on honestly. Lots of slip angle is where they make peak grip (not to be confused with overdriving!). Don't do anything exceptionally well. I have no personal experience in the wet so can't comment on that, but I've heard they're not great. Probably not worse than the V730 if I had to guess.
Continental ExtremeContactSport (ECS) - fantastic all around daily tire as long as there's no snow, and also excellent rain (standing water) tire on track. Have been replaced by the ECS 02 which by all accounts is better in every way.
Additional notes: These are insanely good for a daily driver tire. Sidewalls aren't silly stiff like the super 200TW tires so will feel more numb by comparison. Where these shine is in the wet on track though. If it is raining hard and there is standing water, these or the ECS 02 are the tires of choice. The Michelin PS4S are a comparable tire but I've not run them on anything for any real amount of time to personally comment on. I originally bought a set for my wife's Mazda2, and paired with really lightweight wheels they made the car a LOT of fun to toss around on the street. Found out just how good they were in the wet, so bought ANOTHER set of them for my own Mazda2 for rain track use and daily driving. I actually just recently bought a full set for my GTI. I picked up a free set of bummy looking 17x7.5 OEM wheels which are currently getting painted. I will be putting some 215/50R17 ECS on them. Why smaller than stock? They're strictly for standing water on track. Smaller overall diameter = lower COG also. Plus if you haven't checked out the Tirerack test on wheel vs tire width... this is worth reading/watching the video:
https://www.tirerack.com/tires/tests/testDisplay.jsp?ttid=296