This is personal opinion.
I own few Rats, Avispa and Zancudo, as you can see from the picture below. The Zankudo and all of the Rats are heavy users.
Lately I've being using mostly the Rat with D2 for understandable reasons - the steel requires less sharpening for what I'm using it.
I will always go with linear lock before I use frame lock out in the elements, that's why I personally prefer Rat line of knives.
The only Rat I cannot stand is the Rat2 with the AUS8 steel, I will not trash the whole line but will say that my knife came with steel so soft it was getting dull when you show a piece of paper to it... It is disassembled and waiting for a new blade project.
The Rat line is easily customizable, plenty of options on the scales, replacing worn standoffs and so on, the frame is built as a tank and will last for a long time.
D2 model is outstanding, very little care for the metal of the blade, good HT, I'm very happy with it and using it along with my Gail Bradley 1 and my Griptilian.
The Avispa is very comfortable to hold, the blade is more "bushcraft" oriented as geometry (IMHO) and the knife is overall well designed and built even the frame lock is (IMHO) there to appear to the city folks...
The design problem with this knife is the way they positioned the clip -it stays completely over the lock bar and in my case it is impossible to unlock the blade using one hand. For knife with such profile, this is ridiculous design execution (IMHO). I have a post from few years back, here in this forum, asking why they did it that way, if I remember correctly nobody gave an adequate answer...
As one can see from the picture, the clip on the Zancudo covers half of the frame, therefore not interfering with the lockbar.
As one can see also from the picture below, my Avispa have Benchmade clip in order to achieve the same effect, otherwise I have no use for this otherwise good knife.
Both Avispa and Rat1 have identical blade thickness at the back and identical width of the blade with full Flat grind, it looks like that Avispa have slightly more pronounced belly but this is optical illusion, they are almost identical profiles with the Rat1 edge. Avispa only have clipped point, compared to the Rat blade geometry. The Rat's edge is longer than the Avispa, one more thing for consideration.
My choice would be the D2 Rat1 because of the better steel, design and more options for customization.