Hum let me see,
- Heavier payload capability, nothing aside from SLS matches Falcon Heavy. There are missions like Europa Clipper or Lunar Gateway which just can't be launched on any other launcher. Aside from fairing size, it still has more capacity than Vulcan or New Glenn.
Falcon Heavy is something Elon wants to axe but Gwen won't let him since they have contracts. They only launch the F9H once or twice a year and it can be a couple of years between launches. That's a lot of infrastructure on standby for that cadence. The Delta IV heavy was retired since it was dated and there wasn't enough work for it. F9H can take more mass to LEO than a fully kitted out Vulcan, but whether that is useful would take an analysis of what's been going on the F9H to date. New Glenn still hasn't launched so it's impossible to evaluate. Their specs might change when they have one flight under their belt. Starship turns to maybe have 30T of capacity to LEO, but Elon had to admit that they aren't anywhere near 100T with the version they've been testing which goes to demonstrate the chicken/math law.
- Shorter lead times. You can have a launch within weeks if not sooner as opposed to years which used to be the industry standard. Will say Firefly did a demo with less than 24 hours notice which was very impressive.
No, you can't have a launch within weeks. There's also no reason for it. If you are building a payload, The choice of launchers is going to be narrow and there's always a lead time for launch site scheduling, integration and check out. Nobody has a completed payload and suddenly discovers they haven't contracted for a rocket to put it in space. If you need to switch providers, there's going to be a lead time to create and check out a new payload adapter.
- Cheaper costs. Cost per kg has never been lower.
Launch costs aren't a huge line item in terms of a whole project. Being cheap means the company has less money for R&D, maintenance and building/repairing infrastructure. It's one thing to optimize pricing to sell thousands of bags of dried pasta and something quite different to operating a business that does it's thing a few times a year. Average margins go right out the window since there's a much greater standing cost regardless of cadence. You can't just look at the incremental cost of each launch and mark it up by 20% and be a healthy company.
-Not sure where you are getting your costs for Commercial Crew, the extension prices have gone up to $72m per seat. Starliner is around $90m. Soyuz is around $80m to $90 depending which way the winds blowing.
SpaceX is up around $85mn per seat to ISS with all prices, fees and charges added up. Keep in mind that the US government is paying for Cape Canaveral and not all of the costs for a F9 astronaut launch are captured in the launch site fees. In buying seats from the Russians, there isn't all those outside costs so it's simpler to say what the price is.