Packt books used to be good, their paper and cover quality aren't good.
Nowadays, it seems like they're trying to output as many books as possible regardless of the qualities. Most of the books are around 100-150 pages ugh.
On the other hand, Manning Publishing keep on taking my money, I really hope they start putting out book quality similar to Packt so I can stop spending money on them.
O'Reily have some really good book too like wise with No Starch Publishing. No Starch Pub have some of the best book material I've ever encountered minus web design books. Pragmatic Bookshelf have some quality books too and classic.