I had a tiger loach (botia hymenophysa). It was very brutal and dominated the tank until it met an untimely demise at the hands of my children. It had a very nice pattern and did not care to take any specific territory.
I have a sun loach (botia eos) which became very territorial as soon as the tiger loach was gone. Constantly picking on the skunk loaches. I moved it to the 10gallon tank when I introduced my rams to the 29gallon. This guy "flashed" his "blades" at me one time when we were looking at eachother.
There are two skunk loaches (botia morleti) in my 29 gallon. Due to my large initial population of snails they have grown quite fast. While they occassionaly bother the corys (just the dominate skunk really) they usually don't act too aggressively. I may be moving these guys to my 10 gallon with the sun loach as it was less reclusive when it had some other loaches to bully around. Only the submissive skunk will lay on its side and only when the dominate skunk is nearby. It is great to watch these guys going after flake food.
I have just recently acquired a yo-yo loach (botia almorhae). This was actually the loach I wanted but I could not find it for awhile (except at extortionist prices). Less aggressive than any other loaches I have had and also less reclusive. This guy will try to school with the skunks or the SAEs and they swim away thinking it is being aggressive. This guy exhibits the sleeping sideways behavior that loaches are known for and upon initial introduction he spent the first few hours searching every plant for snails.