best firms for articleship in hyderabad

Rather than looking for Best firms, you should actually plan out what profile you are willing to work in. If you opt for big 4s, you will be working in the same profile for 3 years, whereas in Mid size firm, you will have the opportunity to work in different areas including Audit, Taxation, transfer pricing which have different deadlines.

name some mid size firms in Hyderabad

Not from Hyderabad. you will have to Google it out.