I'd personally say Nickel 45-105 roundwound in practically any reputable make, all the Rock thump you will ever need on a P-Bass/J-Bass. Having said that, use anything you like really, your current Rotos will do just fine. Avoid anything too thin though, Metal and 35-85 doesn't sound too good, too much flap and too much fret collision when you dig in. Stainless Steel will give a much more modern up to date Metal sound, but will mash your frets quicker. I'd just stick with the Rotos as thats what you like and are used to, and I doubt the rest of the band will complain about the subtle nuances of your bass tone for at least the first 5 rehearsals. If/when they do, then you have a reference point to what sound they are expecting of you, then come back here and get more advice.
Witterth: One of the best Rock players in the world uses 50 gauge flats, fingerstyle, and he has absolutely no loss of top end