What is the best EUB that you have tried that gives good body contact?--Meaning that the EUB is easy to hold / makes playing easier / and you are not fighting the instrument?
The Alter Ego Basso is my favorite... as evidenced by my avatar. It feels most like a big bass to me; and you can actually change the angle of that large bout a little if you like standing slightly behind the instrument.
Depends on how you play it. Seated is my prefered position now, and helps to get the bass fully stabilized.
I agree with eub player. I always play the bsx allegro sitting. I don't even use the tummy rest . It takes a little while to get used to it. If I'm playing a standing gig or jam I use the DB. The Eminence has a special end pin that doesn't wobble and I've seen lots of folks play it standing. If you're not trying yo get a DB sound , lots of guys play stick basses that come with stands.
The best way to not fight the instrument is to use a tripod or tom-stand instead of an end pin. It isn't a DB, you don't have to hold it like one.
Although they're not manufactured anymore, Azola basses are surprisingly comfortable in this respect. I didn't think they would be, since the body support is essentially a twisted piece of metal. But the balance is right and the fit is good: the ergonomic essentials have a good equivalence to playing a double bass. Try one if you get the chance.