Question..

You need to give us a lot more to work with. What kind of music do you play? How loud is your band? How large a venue will you be playing at? What kind of bass do you play? Do you want huge rumbling bottom end or a more mid-heavy tone? And perhaps most importantly - how much can you spend? We can make a lot of helpful suggestions if we can know more about you.

To give you a partial answer though, from my experience with GK amplifiers I can definitely suggest them. I've seen some of those heads and cabinets last through ridiculous abuse and still sound great night after night. I have heard virtually nothing bad from anybody I know who has owned a GK.

 

I had the opportunity to try a GK 1001RB-II for a while and I really liked it. Very good quality, very good tone and very powerful!
It is also very affordable as well.
My vote is for the GK!

 

My vote goes to Genz Benz - the most underrated amp manufacturer around. If I were to get one it would be the GBE 600 because of the solid state and tube mix on the preamp. I played one through a Bergantino HT112 and with only the SS portion on, it sounded exactly like GK. Turn the tube drive up and there is a noticeable warmth and phatness that gets injected into the preamp. The shape buttons really make a difference and the the frequencies were very well chosen for the eq.

I put it above GK, but then again it is a little more expensive.