Vishal Bus is my always preference from last 8 years almost. Positives are - I have never seen bedbugs, non-working windows. Always seen cleanliness inside the bus. Seats are also very comfortable compared to Sugama Buses.
Some negatives are : Almost all are well-behaved drivers and cleaners but some are very rude, for example, One bald fellow named "Shashi" - the driver is very rude I felt in my previous travel. And also, one more negative point is - seats were torn little bit - but this is not reducing the comfort level or will not harm our sleep, but bus people need to consider this point.
Other than that, all is well.