If you want personality and since you have a large tank you could always get an Adonis Pleco. They are very large, the average is 2', but the can and do get up to 3.5'. It's been said that the min. tank size is 125g but I think that's being unrealistic. I wouldn't put an Adonis in anything smaller than 200g, so your 250 would be OK.
They are Black with white spots when they are Juvi's, but the spots fade as they age. By the time they reach adulthood they are a solid shiny black and gorgeous. They can be skiddish at times but when they do come out to play the are clowns. They are best kept just one per a tank, they are territorial with their own kind.
Here are a few examples of the Adonis Pleco. The top 2 are Juvi's and the bottom 2 are Adult's, the last having be caught in the wild. Which is why he is as large as he is.
If I were able to have a tank large enough for one of these, I wouldn't think twice about getting one. They are an awesome center piece fish.
One last thing, they go through driftwood like a Beaver does trees.