The Leopard 2 is the only NATO tank to have performed passably in Ukraine, but its service there did reveal quite a few critical design flaws, such as its extremely thin roof, side, and rear armor, which paired with the very vulnerable turret bustle ammo storage, made all Leopard 2 tanks into extremely easy targets for FPV drones. The Leopard 2 is also easier to disable than Soviet/Russian tanks of comparable age due to its terrible roof and side protection, which means that usually only one drone will be enough to not only immobilize it, but light it on fire, vs. the average of 3-4 needed to actually destroy most Russian tanks. Dismounted tank crews tend to have a very short life expectancy on the battlefield due to the ever-present FPV drone threat, so a tank that's easier to disable will lead to higher losses not only for its crew, but also for the soldiers it was intended to support who now are attacking/defending without tanks. So while its probable that slightly fewer tankers have died inside their Leopard 2s, it's also likely that their fragility has cost more lives than the explosive tendencies of Soviet tanks relative to the amounts of each that have been fielded. Though do know that I've seen a lot of gory pictures of freshly disabled Leopard 2s to know with certainty that the aura of Leopard 2s and other western tanks having "the best survivability" is a carefully curated image maintained by unfortunate Ukrainian soldiers who have to retrieve the bodies of vehicle crews under cover of night, and who have on occasion written utterly gut-wrenching accounts of how they've had to pull bodies wedged into turret rings by explosions out in pieces.
Also, the whole "better optics" thing is just a holdover from the Cold War, as the Soviets weren't able to mass-produce thermal sights, so they didn't put any on their tanks, with the Post-Soviet Russians only starting to put thermals on their tanks in 1996 with the T-80UK. However, the Russians would finally figure out mass-production of thermal sights in the early 2000s with French help, with the T-90A being the first mass-produced Russian tank to have thermals, with every Russian tank produced or upgraded since having a thermal sight at least for the gunner, with only T-90M and T-14 Armata having a Commander's Independent Thermal Viewer (CITV). However, the only two tanks in Ukraine's entire arsenal as of 2023/24 with a CITV are their Leopard 2A6s (Leopard 2 didn't get a CITV until Leopard 2A5 in 1995) and their two prototype T-84U Oplot-Ms (the original T-84 used a 3rd generation night vision sight but no thermals), so both sides are equally falling short in this regard.
The Leopard 2 is the only NATO tank to have performed passably in Ukraine, but its service there did reveal quite a few critical design flaws, such as its extremely thin roof, side, and rear armor, which paired with the very vulnerable turret bustle ammo storage, made all Leopard 2 tanks into extremely easy targets for FPV drones. The Leopard 2 is also easier to disable than Soviet/Russian tanks of comparable age due to its terrible roof and side protection, which means that usually only one drone will be enough to not only immobilize it, but light it on fire, vs. the average of 3-4 needed to actually destroy most Russian tanks. Dismounted tank crews tend to have a very short life expectancy on the battlefield due to the ever-present FPV drone threat, so a tank that's easier to disable will lead to higher losses not only for its crew, but also for the soldiers it was intended to support who now are attacking/defending without tanks. So while its probable that slightly fewer tankers have died inside their Leopard 2s, it's also likely that their fragility has cost more lives than the explosive tendencies of Soviet tanks relative to the amounts of each that have been fielded. Though do know that I've seen a lot of gory pictures of freshly disabled Leopard 2s to know with certainty that the aura of Leopard 2s and other western tanks having "the best survivability" is a carefully curated image maintained by unfortunate Ukrainian soldiers who have to retrieve the bodies of vehicle crews under cover of night, and who have on occasion written utterly gut-wrenching accounts of how they've had to pull bodies wedged into turret rings by explosions out in pieces.
Also, the whole "better optics" thing is just a holdover from the Cold War, as the Soviets weren't able to mass-produce thermal sights, so they didn't put any on their tanks, with the Post-Soviet Russians only starting to put thermals on their tanks in 1996 with the T-80UK. However, the Russians would finally figure out mass-production of thermal sights in the early 2000s with French help, with the T-90A being the first mass-produced Russian tank to have thermals, with every Russian tank produced or upgraded since having a thermal sight at least for the gunner, with only T-90M and T-14 Armata having a Commander's Independent Thermal Viewer (CITV). However, the only two tanks in Ukraine's entire arsenal as of 2023/24 with a CITV are their Leopard 2A6s (Leopard 2 didn't get a CITV until Leopard 2A5 in 1995) and their two prototype T-84U Oplot-Ms (the original T-84 used a 3rd generation night vision sight but no thermals), so both sides are equally falling short in this regard.