The clip point and insingo are both great utility blades - either will work fine, so you should get what you think looks nicer, and you will not be missing out on any CRK features.
The small and the large are both great knives -
The small 21 will be smaller than any of the knives you listed, but it probably wont feel too tiny, if you are looking for a smaller knife. The weight and blade work great for me (size L or 10 glove)
The large 21 is a smooth knife and I consider it the flagship model. Cannot go wrong, and it is probably why you are considering a CRK. Larger than the small (of course), but still reasonable enough that I feel fine carrying it anywhere - church, school, work, etc.
The 25 is heavier and opens with more authority. It has a thicker and a wider blade, and the high hollow grind is a great cutter. It is also a great choice.
The Umnumzaan is also a great choice. They sometimes go for cheaper than the other offerings, which is great if you don't mind getting a knife on the secondary market. I love the engineering, and it is just as smooth and precise as any CRK. This was my first CRK and got me hooked on many others.
The Inkosi is also great - much smaller than any other knife, but if you don't mind small knives, it is a beauty. The size makes it probably my most utilitarian knife, because it is too tiny to sit and flick it around. I think a lot of these hit the forum market because of how unexpectedly small they were, but again, I love mine.
Don't know anything about the Ti-Lock, and frankly, my biggest draw to CRK is the ability to break down the knives completely, so the Ti-Lock, which (as far as I understand) does not fall under the same choose-your-own-maintenance-plan CRK warranty, doesn't interest me much.
The great thing about Chris Reeve Knives is that you will probably love any knife you can get. I would recommend finding a good deal on any knife in the forum exchange (as long as it hasn't been modded past its warranty) and give it a shot.
Make sure you post and write about what you end up with!
