I love my Sunbeams. I have them on all four of my basses.
If you want to go flat-wound, I recommend Thomastik. I have used both the Jazz Flats and D'Addario Chromes. Both sounded great on E, A, D, and G. But the Chromes were a dull thud on the low B, where the Jazz Flats had true tone. I had good experience tone-wise with Thomastik Jazz Rounds as well - a kind of in-between if you will. But they were just to light for the bass and I didn't want to send it in for a heat-bend. The strings sounded good, but not that good.
AND, I used the good old CX3s for YEARS with absolutely no complaint.
As is said so often, just pick a set and try them. Every string reacts differently on every bass for every player.
The Thomastiks are the only ones I would call pricey - and they're cheap compared to what I pay to string my upright.
Have fun in the search!
C-Ya.........wayne