In terms of quality, Spyderco does not come close to CRK.
There are some other production titanium framelocks out there. The Skirmish, the Alias, the Buck TNT etc... They are great knives and do compare to the Sebenza, and are cheaper. But the quality, fit, and finish are not as good as the Sebenza.
The other high-end production companies like William Henry and Strider do not have CRK's level of quality.
The knives that match the Sebenza in terms of quality are customs and cost as much or more.
The Sebenza isn't the end-all, be-all of knives. I, personally, would rather have a Tom Mayo TNT than a Sebenza (and I will be buying one soon), and I recently handled a John W Smith titanium framelock with a G-10 onlay that blew me away more than my Sebenza does. I will be buying it soon as well. But those are customs. IMO, and the opinion on many, in the production knife world, the only folders that can match the Sebenza in terms of quality are Mnandis. That doesn't mean CRK makes the best production knives since there are so many subjective issues to consider. Some may prefer a Ka-Bar Dozier to a Sebenza. Or a Spyderco Police, or Military or whatever. But in terms of quality, yeah, CRK are pretty much tops.
There are some customs that cost around the same as the Sebenza and have the same quality. The main advantage of a Sebenza in that comparison is that it is easier to buy (more accessable), and replace.
If you don't have an eye for detail, then a Sebenza might not be for you. You might be just as happy with one of the Sebenza's less expensive production titanium framelock alternatives like the Buck TNT, or Skirmish. I own those as well and they are great knives. The Sebenza is a little bit better than they are due to the superior details, but it also costs more than twice as much. So it is up to you whether those details matter enough to you. For me, they do matter so I did buy a Sebenza, but I didn't stop there and will continue to buy knives that are cheaper *and* more expensive than the Sebenza, such as Spydercos, Microtechs, Benchmades, and Tom Mayos, Rick Hinderers, and John W Smiths. They all have their own appeal.
The law of diminishing returns is true. At the higher prices, you need to pay a lot more to get a little more. But as a knife knut, I am willing to do that.
Also, I want to second the opinion that Striders are fantastic knives and are very well-built. I have seen the complaints and I have seen Mick act like a jerk, but every single Strider I have laid my hands on what a fantastic and well-built knife. I think the SMF/SNG is the best functional user design in the world of folders. Period. Obviously that has a lot to do with my hands and how well they fit me. Some find them uncomfortable. But ergos aside, the designs are extremely functional and well-thought-out.