I went through this exact same thing. My birthday was a week ago, and I had about $400 to spend completely on myself. I spent weeks, literally, scratching my head and the choice was between a Sebbie or a Strider.
I have 4 Sebbies, but I had my eye on a Strider SNG or SMF for years now, but the price kept me away. Plus the pivot pin on a Strider takes a special wrench to tighten, most people don't have one, so getting one from the States and having it confiscated by Canadian Customs because they flicked it open due to a loose pivot didn't appeal to me. But I found an older (pre-Hinderer) SMF in Canada here on Bladeforums, so no hassles with Customs, and ironically it came with a wrench too...
This is an SMF I'll talk about, not SNG, so the SNG is about an inch OAL shorter.
Anyways, like many people here said, it's really hard to compare them.
Anyway, Sebenza is overall thinner, slimmer, narrower. Strider is therefore thicker, larger, wider everywhere. In terms of handle thickness alone, it's a full Sebenza scale thicker than the Sebbie. Handle with is about the same at the pivot, but then the Strider tapers off to almost double the width at the pommel. This widening of the Strider handle actually lets you apply significant torque with a minimum of effort, so stab and twist is extremely easy. And the large teeth on the handle and blade spine work really great, especially if you're wearing gloves, but will wear out your palm with use without gloves, at least it did for me. Sebbie usually has small gentle teeth on the blade spine, though my newer Large Classic has larger teeth, but still nowhere near as aggressive, and I actually prefer the old style teeth.
The SMF I have has a flat grind, and blade is pretty thick (so it'll wedge itself in some stuff), but conversely you can use the knife as a prybar if you have to. The SMF blade spine thickness is close to double of the spine thickness of the Sebbie. I can't measure them right now, so going from memory here. And that kind of sums up the Strider for me. It can cut, but it can do things a fixed blade or a hatchet can do if you really need it to. It's big and heavy and has a monster of a pivot pin and the G10 scale and backspacer are milled from a single piece of G10, so it's real solid. Ti scale is thicker too. So just overall it's big and thick and the handle at the pommel is wide so you can apply some torque while not worrying about the blade chipping because it's a thick and flat grind, whereas a Sebbie handle won't give you a handle surface to apply as much torque, and the hollow grind and relatively thin tip might break or chip.
Of course a knife is not a prybar. If it comes down to cutting, Sebenza will probably win. But if the knife you have is supposed to serve as anything from a knife to a shovel, a hammer, an axe, then Strider will probably fare a lot better than the Sebbie. But if you just want an exceptionally good knife for cutting, then you can't go wrong with a Sebenza.
The SMF and Large Regular Sebbie have about the same cutting edge length, so an SNG will have a cutting edge slightly shorter than a Large Sebenza. The Strider choil on the blade allows to really choke up on the knife though, and also if you grab the very pommel of the handle (and there's plenty of it to grab) you can be far away from what you're cutting with the edge (cutting though a root at the bottom of a hole in the ground, for example).
When I got this Strider SMF though, I immediately fell in love with it. The ergonomics really work for me, but I read that it feels wrong to some people, and I often see people going from SNG to SMF and vice versa trying to get a handle that feels comfy. So I'd just sit with Large Regular Sebbie (my user knife) in one hand and the SMF in the other, and try opening them with gloves on and off, different grips, cutting, etc. Sebbie is a wonderfully build knife for cutting, and carries really well. Its handle shape is universal, so it feels great in any hand and any grip. But I can see a Strider handle feeling wierd in hands smaller than mine, it's bornering on huge even for me. Sebbie is large enough and solid enough to cut just about anything you put in front of it, without any overkill. It'll do what you ask it to do, and stop there. But that's where Strider begins. Strider is a monster, with what feels like overkill in just about every respect: far too thick, too heavy, too wide. I can picture breaking off a tip on a Sebbie pretty easily (I've done that with enough knives by now by accident), but holding the Strider I think I'll need a vise to take a chunk off of it, just stabbing and twisting and turning won't do it. I don't have enough muscle to break it, where I'm pretty confident I could manage that with a Sebbie if I really, REALLY wanted to.
I carry them both in sheaths so size doesn't bother me any. Strider does have a pretty standard clip, held by one screw and a hook on a clip going into a hole in the TI scale, preventing the clip from moving around. But the clip still moves around quite a lot. Sebbie clip is better by my standards, it doesn't move around and has a dimple halfway up for additional hold so the knife doesn't sway in the pocket.
And that's about it, really. SMF just looks like a complete overkill for 99.9% of the tasks I put in front of it. But when crap hits the fan, I think I'd rather have it than a number of other knives. But as far as a choice between a Sebbie and an SNG? For everyday stuff I'd go with a Sebbie, I don't run into things that requires anything a Sebbie can't handle. But for outdoorsy stuff or when you just don't know where you'll end up I'd go with a Strider, it has a clearly indestructible feel to it, I'd be perfectly comfortable digging and prying with it without a worry in the world, I'll probably break before it does.
Another thing to consider, I haven't had any experience with warranty work with either CRK or Strider. But Strider seems to have a rock solid warranty of "If you break it, we'll fix it." while CRK is based on conditions along the same lines as Spyderco, Benchmade, etc. I have had warranty work done at Spyderco and was extremely happy with the results, so it's by no means a minus to a Sebbie.
I can snap off a few pictures of used Sebbies and SMF (it wasn't NIB, so it was used before it got to me, and I put it though some stuff already too), but I don't know how useful it will be if you aim for SNG.
