Is it possible to sit down for your gigs, and not use a strap ?
I way prefer sitting down on gigs, but most of my gigs are jazz, so sitting down is acceptable. I went and splashed out on a really nice stool a few weeks ago, so I'm sitting, but it's actually more 'propped', because it's set quite high up, and I don't use a strap.
I've got one of these, not cheap, but for me it's brilliant. [attachment=200680:71Vr8kuk1ZL._SL1500_.jpg]
For straps you maybe want something that doesn't contort and sink into the muscle between your shoulder bones and your neck. I've used a comfort strap, and found that these really sink into this area, restricting the blood supply to your arm. A wide, padded leather strap, or a Mono (if they're not too long for you), is best.