Depends on the bass the amp really for me. If its my passive P-bass played with any solid state head, I'll generally run it into an English Muff'n then into a Sansamp Bass Driver into the head. General pretend your going through an Ampeg settings which sounds fine in a rock band situation, but lacks definition for any slap, tapping and solo stuff.
With any kind valve amp, I try and run as few effects as possible. I'd be open to a bunch of pedals, but I'd rather just have a good amp. I've found that a Vigier Excess run into an EBS Fafner doesn't need a lot of tweeking! I turn the bass to between 2 and 3 o'clock, take the mids down a touch around 600 Hz, but depending on the room, yada yada yada...
Obviously, the most telling factor on tone will be your fingers and your attack. Also,string type, string gauge, action height, and pick ups all have an impact on tone..
A good bassist will be able to manage to make an entry level bass and amp sound have decent tone, but I still think that basses, amps and cabinets do play a role.This is especially the case when plugging a bass straight into an amp. I know its subjective, but for me there is a big difference, for example, between a Squier J-bass through a Crate combo and the same bassist plugging a Sadowsky into a Markbass combo. I know there are people that think its more impressive to make 'cheap gear sound great' than to just have good gear. However, I think these people are missing the point. Gear is an aid, not the determining factor on whether you can get a good sound. If you manage to make cheap gear sound good, it just means you are good, and you would sound impressive through most gear. Its just nice to be able to play through something that doesn't require any modding or a bunch of pedals to help bulk up your sound. It leaves you to get on with playing, which to me is the most important part.